Trying to fill A/C system; blows hot air and high side has low pressure

[jangell]

Hi everyone. I'm trying to fill my A/C system with R134a. This is a new system that has been held at vacuum (and actually holding it) for a year while I got other things in order.

I got it to take about two and a half 12 oz cans of refrigerant. The compressor turns on, so that parts's working. However, the high side reads very low, and I'm getting hot air out of the vents (not warm air -- hot air, like the heater is on, but it's not). The metal of the manifold block itself is also hot to the touch.

My setup is a proper manifold set with the lines correctly connected to the high and low sides of the A/C system. I have an early car, but it has been updated to the later system with the high pressure switch. Literally the entire system is new front-to-back, including the hoses, accumulator, compressor, condenser, evaporator, orifice tube, high pressure switch, etc. I made sure to pull vacuum on the system to vacuum, but it was already sitting at vacuum so that wasn't really necessary.

Any idea what I'm doing wrong?

Here's a picture of the gauges with the engine and compressor running:

60564

And with the engine off:

60565

Thanks!

-- Joe

[David T]

Verify you have connected the low (blue) hose to the suction (low) side and the same for the high (red) side. I think you go them reversed. According to ST-29-11/81 the correct fill is 2.2 lbs but that's for R-12. For -134 you reduce the fill 10% so that is 31.6oz. You got 30 in there so you should have the correct fill. As for why it is blowing hot, get the gauges on right and see what your pressures are. The low pressure switch must be adjusted to use -134.

[Rich]

It looks like the manifold gauges are reading in reverse of normal with compressor on. The low side reads like the high side should and vice versa. Am I reading that correctly?

That, along with zero cooling, suggests the new hoses or something else might be connected backward.

You report that you're sure the refrigerant is flowing the right way with correctly connected hoses. Possibly worth another look just in case?

Now seeing David T. already replied similarly.

[DMC-81]

Hi everyone. I'm trying to fill my A/C system with R134a. This is a new system that has been held at vacuum (and actually holding it) for a year while I got other things in order.

I got it to take about two and a half 12 oz cans of refrigerant. The compressor turns on, so that parts's working. However, the high side reads very low, and I'm getting hot air out of the vents (not warm air -- hot air, like the heater is on, but it's not). The metal of the manifold block itself is also hot to the touch.

My setup is a proper manifold set with the lines correctly connected to the high and low sides of the A/C system. I have an early car, but it has been updated to the later system with the high pressure switch. Literally the entire system is new front-to-back, including the hoses, accumulator, compressor, condenser, evaporator, orifice tube, high pressure switch, etc. I made sure to pull vacuum on the system to vacuum, but it was already sitting at vacuum so that wasn't really necessary.

Any idea what I'm doing wrong?

Here's a picture of the gauges with the engine and compressor running:

60564

And with the engine off:

60565

Thanks!

-- Joe

Hmm, that's weird. Are you sure the hoses ( both A/C and manifold) are not connected to the wrong ports? Also, here's a handy troubleshooting chart.

https://www.apairinc.com/downloads/get.aspx?i=73849

Edit: Other posters beat me to the punch.

[jangell]

Thanks — I thought I had them hooked up correctly, but it’s possible that I don’t. I have the blue (low) line connected to the side of the compressor closest to the edge of the car, and the red line connected to the side closest to the engine. I’ve attached photos. I need to get a longer quick release adapter for the side I have the red hose hooked up to, so I’m just connecting it directly for now.

https://uploads.tapatalk-cdn.com/20190707/4d836fa424dd98da3a04077a24b2b733.jpghttps://uploads.tapatalk-cdn.com/20190707/2ccb2888f7f20b7b82c47651b6ce17e3.jpghttps://uploads.tapatalk-cdn.com/20190707/2f5c51ef1aaeb89b00c617be1cadb0ca.jpg

— Joe

[jangell]

So I found the thread where I asked what compressor to get for a 3.0L conversion, and went with a Four Seasons 58555 (Sanden SD709). There was also a picture of a similar compressor installed, and it clearly has the high side at the edge of the car and the low side closest to the engine: http://dmctalk.org/attachment.php?attachmentid=55214&d=1495250162.

I can't actually find any useful information about which side of the compressor is the high or low side (from Sanden or Four Seasons).

Now the question is if I just have the manifold hooked up backwards, or the actual A/C lines hooked up backwards. I don't recall if the hose connections to the compressor are different sizes or not.

Also, I know you're not supposed to fill from the high side, so I'm wondering if I've done anything particularly bad there.

I'll swap the manifold hoses and try again. Thanks!

-- Joe

[jangell]

Ok, so I think the hoses in the AC system itself are set up right — the driver’s side hose from the condenser goes to the passenger side of the compressor.

So it’s just the Manifold lines that are swapped.

I’ll report back once I’ve tried filling it with the hoses hooked up correctly. Thanks!

— Joe

[Ron]

At the compressor, the high side hose/pipe always has the smaller diameter (the coolant is compressed so it has less volume...).

The high side compressor port should have an "D" and the low side an "S", if marked.

I doubt you could put 2.5 cans in the high side with those pressures w/o blowing up the can???

Be carefull!

[jangell]

More likely I’m very bad at gauging how much the cans weigh full vs empty, or that something was leaking. I certainly vented some refrigerant when disconnecting my side can tap, but my understanding is that that is normal. No cans have exploded on me, so that’s good. :)

Also, both of my hoses are the same diameter, so I don't have a good way to tell by sight. I finally just traced the hoses from the compressor, given that the driver's side one goes to the condenser and would be the low pressure side. The way the hoses cross each other at the compressor threw me for a bit, and it's easy to miss that in the parts manual diagram as well.

I’m at the car now with the engine running and have 40 PSI on the low side and 350 PSI on the high side (it’s 78 degrees ambient). The compressor has been running the entire time, and the vents are still blowing hot air. It was still going up when I turned the car, so now I’m guessing that I’ve overfilled it? Still Dortmund explain the hot air, though...

Thanks!

— Joe

[Bitsyncmaster]

At the compressor, the high side hose/pipe always has the smaller diameter (the coolant is compressed so it has less volume...).

The high side compressor port should have an "D" and the low said an "S", if marked.

I doubt you could put 2.5 cans in the high side with those pressures w/o blowing up the can???

Be carefull!

+1
But I think DPI uses one size hose for both.

Only open your low side as shown on your gauges when your adding charge. If the low side pressure goes much above 50 PSI shut off the charge until the pressure drops.

[Ron]

If your gauges were backwards, it would make sense for them to read as they do with the charge you put into it. Today (at 80F) you would expect the high side to show 145-190 psi and the Low side 25-32 psi when the compressor cuts OFF, on a stock system w/R12. As David said, 134a pressures are higher and [sometimes] you need to adjust the pressure switch. And it looks like you have about 20psi on the low side, which means your compressor would cut out late. The two could explain the high high pressure.


EDIT: I posted this before I saw your last post, if it is 350 psi now, something else is going on!

Is the receiver dryer/accumulator getting cold?

[Ron]

I finally just traced the hoses from the compressor, given that the driver's side one goes to the condenser and would be the low pressure side.

Basic Hose Routing:
60586

[WHO1DMC]

Double check that the hot water valve is getting vacuum to turn off. After two years I got to mine this summer and found that my vacuum line wasn't holding.

My .02
Dave B.

[Bitsyncmaster]

More likely I’m very bad at gauging how much the cans weigh full vs empty, or that something was leaking. I certainly vented some refrigerant when disconnecting my side can tap, but my understanding is that that is normal. No cans have exploded on me, so that’s good. :)

Also, both of my hoses are the same diameter, so I don't have a good way to tell by sight. I finally just traced the hoses from the compressor, given that the driver's side one goes to the condenser and would be the low pressure side. The way the hoses cross each other at the compressor threw me for a bit, and it's easy to miss that in the parts manual diagram as well.

I’m at the car now with the engine running and have 40 PSI on the low side and 350 PSI on the high side (it’s 78 degrees ambient). The compressor has been running the entire time, and the vents are still blowing hot air. It was still going up when I turned the car, so now I’m guessing that I’ve overfilled it? Still Dortmund explain the hot air, though...

Thanks!

— Joe

Are your running a standard orifice or the variable one?

[jangell]

I'm just really good at getting myself confused with A/C hose routing, apparently. :)

At the very least, swapping the manifold hoses made the pressure readings make more sense.

Here's a better picture of how the hoses are connected to the accumulator. The "H" marking is irrelevant, and is because I thought that was the high side. I'm still trying to decide if I swapped the actually A/C lines or not.

60587

-- Joe

[jangell]

Are your running a standard orifice or the variable one?

Standard, I believe.

-- Joe

[jangell]

Is the receiver dryer/accumulator getting cold?

It is not -- in fact, it's extremely hot, and hard to hold onto for more than a second or so. The pipe that runs across the front of it is cold, but the accumulator itself is very hot.

-- Joe

[jangell]

Oh, here are the gauges right after turning the car on:

60588

And after a few minutes of running (I forgot to time it; I shut it off rather than waiting to see where it stopped at):

60589

This was for my test of the accumulator temperature, so it's a reading I just took.

-- Joe

[Bitsyncmaster]

My bet is you have the orifice in the pipe leaving the accumulator. If that is even possible. I say that because your compressor is working but your getting hot air from the evaporator.

[jangell]

I don't think I do -- I made sure to install it in the pipe where the original one was located. Of course, the only way to be sure is to remove the accumulator, I guess.

Before I do that, anything else I can look at? :)

-- Joe

[WHO1DMC]

I also had a problem with the new orifices tubes not fitting properly. I had to trim the nubs on the back side off or it would be to tight and crush the thing and of course not work.


Dave B.

[Bitsyncmaster]

I don't think I do -- I made sure to install it in the pipe where the original one was located. Of course, the only way to be sure is to remove the accumulator, I guess.

Before I do that, anything else I can look at? :)

-- Joe

If your not sure what orifice you installed you may want to pick up a new standard one. I'm not sure what the variable orifice would do if installed backwards. The standard one would work either way but the filter screen may not do it's job backwards. If no orifice was installed you would not see much high pressure.

[Ron]

Before I do that, anything else I can look at? :)

-- JoeThe pressures you see when you first turn it off are almost worthless...
1. You need to run it a little above idle and record the high and low side pressures when the compressor cycles OFF.

2. Go back to the diagram I posted and double check the routing. Also, compare the temps in the chart too*, IE, Red lines are hotter than Blue. E.G., immediately before the orifice tube should be hotter than after (downstream) of the orifice tube, etc.

My guess is you have the gauges correct now, but you may also have a line crossed *(because the Accumulator = Receiver Dryer in the diagram is too hot).

If once you get it where the accumulator is getting cool, it don't blow cold, you may have a door in the air box not acting correctly and/or water valve, as mentioned, or something else wrong as well.

[Ron]

If your not sure what orifice you installed you may want to pick up a new standard one. I'm not sure what the variable orifice would do if installed backwards. The standard one would work either way but the filter screen may not do it's job backwards. If no orifice was installed you would not see much high pressure.
+1
Imo, whatever orifice he has is working, so he needs to figure out why the accumulator is getting hot instead of cool before taking things apart....

[jangell]

If your not sure what orifice you installed you may want to pick up a new standard one. I'm not sure what the variable orifice would do if installed backwards. The standard one would work either way but the filter screen may not do it's job backwards. If no orifice was installed you would not see much high pressure.

I ordered a new tube and an accumulator for good measure. I got the original from DMC MW, so I assume it was standard, but they’re cheap so I ordered extras just in case.

— Joe

[jangell]

The pressures you see when you first turn it off are almost worthless...
1. You need to run it a little above idle and record the high and low side pressures when the compressor cycles OFF.

2. Go back to the diagram I posted and double check the routing. Also, compare the temps in the chart too*, IE, Red lines are hotter than Blue. E.G., immediately before the orifice tube should be hotter than after (downstream) of the orifice tube, etc.

My guess is you have the gauges correct now, but you may also have a line crossed *(because the Accumulator = Receiver Dryer in the diagram is too hot).

If once you get it where the accumulator is getting cool, it don't blow cold, you may have a door in the air box not acting correctly and/or water valve, as mentioned, or something else wrong as well.

I’ll try to jack up the car again tomorrow afternoon and see what lines are hot and what lines are cool when the condenser is running. Will be slightly disappointed if the A/C last ne fittings are the same size and easily swapped, because of how simply making the differ not sizes would avoid stupid people making stupid error like I did. :)

I should note that at no time was the condenser NOT running so far, so I don’t know what those pressures are, unless I disconnect the low pressure switch. Although the fact that this switch is causing the Compr sword to run continuously may itself be a clue.

I’ll need to check the water valve. I think it’s working, insomuch as the Vent mode temperatures (the one that just runs outside air through the cabin without the heater or A/C seem to match the outside air. I’d expect hot air if it wasn’t working, right?

Thanks!

— Joe

[Ron]

The water valve open would make it warmer than normal, but I wouldn't think anything like the heater running. But the doors/flaps might.

I'm assuming you meant "compressor" running all of the time. ...have to add that clue and think a minute...lol

[Ron]

If the compressor is not cycling, the evaporator could be froze over and it would not blow cold...,fwiw, same for overcharged a lot.

The switch should turn the compressor off when it is at the ~20psi seen in the pic.
Can you post a pick of "The pipe that runs across the front of [the accumulator]? post 17

Did you see in the diagram that the high side of the compressor goes to the condenser, not the low side as you posted?? posts 11-12
That would explain it all (especially if you were charging it when it was shut off???).

[David T]

Since you replaced everything you must now double-check EVERYTHING. Verify the output of the compressor goes to the driver's side hose and goes to the condenser coil. Follow the routing all through the system to make sure you have the flow correct. Make sure the fans are moving air through the radiator and the condenser coil and the cabin fan is moving air through the evap coil. When working on a car, to simulate it's moving, I put a box fan in front of it to help move the air around better. Helps to reduce the high side pressures. Since you were putting the refrigerant into the high side I doubt you got 30 oz in. Check that you have oil in the compressor with a dipstick. There is a sketch on the Sanden site to make one and the Workshop Manual tells you how to check it. When you vacuum the system you must get ALL of the air out before you put the -134 in.

[Ron]

+1
Except, I wouldn't rely on where the driver's side hose goes -- The Sanden SD709 comes with several back plates, it can be either way, some even have the suction in the center of the unit.

Whether the charge was being applied while the compressor was on or not is the key. If so, I'd suggest removing the hoses at the compressor and manually turn the compressor to identify the discharge port and confirm they are wrong.
...
Then evacuate it for an hour, recharge it while running, double check the gauge readings, and :burnout:

[jangell]

I meant "compressor", not "condenser". I do that a lot, but I know what I mean. :). Auto-correct was not helping with other parts of my post either.

I had a few minutes to run the system and check the temps. Here's what I came up with:

Compressor, Low Side: Cold
Compressor, High Side: Hot
Accumulator Body: Hot
Pipe "in front" of Accumulator (from Evaporator to Condenser): Cold
Pipe forward of Accumulator to Evaporator: Hot
Condenser, Bottom: Cold
Condenser, Top: Warm/Hot

Here it is as a diagram with pictures. The red/blue dots indicate hot/cold and where I took the readings (by grabbing the hose). The "pipe in front of the accumulator" from my other post is the one that runs from the evaporator to the bottom connection on the condenser, going around the accumulator near the tire:

60605

This does not appear to match the diagram that Ron posted earlier, although I finally realized that the red/blue are for high/low pressures and not hot/cold temperatures, so I'm not sure how much that would actually match up.

Other notes:
- Cooing fans are running (I didn't put a box fan in front yet)
- Cabin fan is running
- The compressor never turns off
- The hoses to the compressor are indeed different sizes (28mm vs 32 mm nuts), so it's highly unlikely that I mixed them up. These were hoses from DMC MW made for R134a. I think I just got myself turned around about the direction of the refrigerant flow the other day. It was over a year ago when I replaced the system, but the car has only been on the road for a few months, and other issues have kept me from getting around to charging the A/C until now.

I'm not sure how to tell if the cabin fan is actually blowing air over the evaporator or not. The mode switch vacuum seems to be working, at least.

I'll have to check the compressor oil later. It came pre-oiled, but I don't know if that means anything at this point. I have not added any oil to the system.

As for which way the compressor turns, I have no idea. There was a green sticker with a bar code and some small print on it. I tried to wipe off some grease with my finger, and I wound up wiping the actual ink of the label. Hopefully that didn't have the specific sub-model on it. :)

Would the evaporator freeze over that fast? I only ran the car for a few minutes. The hoses got cold enough to get condensation on the metal fittings (well, the one going from the condenser to the evaporator, anyway), but would that be enough to freeze it over?

Thanks again!

[Bitsyncmaster]

From the compressor outlet to the orifice should be hot and after the orifice to the compressor inlet should be cold.

[Ron]

+1 Dave

=====

Something is wrong with your diagram -- It can't go from hot to cold to hot to cold. A restriction could cause it to get cold when it shouldn't if there is high pressure behind the restriction. But it would take another compressor to get it Hot again....

The chart is correct, except it calls the accumulator a receiver dryer.
Red = High Pressure = Very Hot/Hot
Blue = Low Pressure = Cold/Cool

I don't get why you say you don't know which way the compressor turns.... (Same as the engine and alternator;-)

If the compressor does not cycle, the evaporator will freeze over. How fast depends on the humidity and the temp & volume of air going over the evaporator.

You didn't answer whether you charged it while running or not.

[jangell]

The red/blue markings on the photos indicate where I took the actual readings. The dots on the diagram match those. The colored lines are more of a guess. The line at the top of the condenser was only warm, though, not "hot", but otherwise everything is as I describe. I can run another test tomorrow, though, just to be sure I got it right.

I know which way the compressor turns from the belt :) -- I just don't know how that correlates to the suction and discharge ports on the compressor.

I did charge it while the engine was running (sorry, forgot to mention that). But there's a big but there -- an electrical issue caused the compressor not to engage, which I fixed when I was on my second can (I though the compressor needed some refrigerant to start running, so I didn't think it was odd that it wasn't on). I just realized that this was important -- it means I put in at least 12 oz on the high side with the compressor off.

Maybe I should just vacuum out the system and start all over again.

Thanks!

-- Joe

[WHO1DMC]

Not trying to be a knit pick but it looks like you're compressor is on its side because the oil plug should be on the top.


Dave B.

[jangell]

Not trying to be a knit pick but it looks like you're compressor is on its side because the oil plug should be on the top.

Dave B.

I actually thought I had the compressor upside down at one point when I was first installing it, but I'm pretty sure I have it right side up now. The mounting frame it came with only fit one way (and ALMOST fit upside down, which is why I was confused), so I'm reasonably sure it's right...

-- Joe

[Ron]

The red/blue markings on the photos indicate where I took the actual readings. The dots on the diagram match those. The colored lines are more of a guess. The line at the top of the condenser was only warm, though, not "hot", but otherwise everything is as I describe. I can run another test tomorrow, though, just to be sure I got it right.

I know which way the compressor turns from the belt :) -- I just don't know how that correlates to the suction and discharge ports on the compressor.

Sorry, let me rephrase it- If you remove the hoses and turn the compressor the way it normally goes (CW), it will blow out of the discharge = high side port and drawn air in on the low = suction port.
Further: When running, it will be very hot out of the high side port and remain high and hot through everything up to the orifice tube. After the orifice tube, it should be cold/cool all the way back to the compressor.


I did charge it while the engine was running (sorry, forgot to mention that). But there's a big but there -- an electrical issue caused the compressor not to engage, which I fixed when I wats on my second can (I though the compressor needed some refrigerant to start running, so I didn't think it was odd that it wasn't on). I just realized that this was important -- it means I put in at least 12 oz on the high side with the compressor off.

Maybe I should just vacuum out the system and start all over again.

Other than the risk of blowing the can or something up, it is ok if you put it in the high side.
I must say I don't see how you could have...the can shouldn't survive 100's of psi.
That be the case, I'd would guess that a hose is wrong at the evaporator (orifice in wrong order, as someone suggested earlier.)
The chart is your friend :smile:
On a D, you should charge it with the can turned up and the engine running.

[David T]

I agree you should start all over again. First recheck all of your connections making sure the compressor discharge goes to the condenser and then to the accumulator, orifice tube, and evap coil returning to the suction side of the compressor. Make sure the compressor is mounted correctly and has the correct amount of the right kind of oil. Pressure test and then vacuum the system finally adding 30 oz of -134. That should get you going. Try not to confuse the low side and the high side. Add the refrigerant to the low side while the compressor is running. Jumper the low pressure switch to get the refrigerant in. My guess right now is you got mostly air in the system, not refrigerant. That's why you aren't getting things cold and your high side is way too high and your low side is low.

[WHO1DMC]

I agree you should start all over again. First recheck all of your connections making sure the compressor discharge goes to the condenser and then to the accumulator, orifice tube, and evap coil returning to the suction side of the compressor. Make sure the compressor is mounted correctly and has the correct amount of the right kind of oil. Pressure test and then vacuum the system finally adding 30 oz of -134. That should get you going. Try not to confuse the low side and the high side. Add the refrigerant to the low side while the compressor is running. Jumper the low pressure switch to get the refrigerant in. My guess right now is you got mostly air in the system, not refrigerant. That's why you aren't getting things cold and your high side is way too high and your low side is low.

Yuuup agreed. Myself I would go for the orifice tube. $2.50 at the parts store. No big deal.

Dave B.

[Ron]

Nope, won't work -- because it goes: compressor -> condenser -> orifice -> evaporator -> accumulator -> compressor instead, like the chart, and the parts manual:

60609
The arrow for the orifice is drawn goofy, it goes where #27 points, in the evaporator tube.

[WHO1DMC]

Oops I didn't catch David Ts accumulator booboo. Ha!


Dave B.

[Ron]

Lmao! ..what ya get for agreeing with him :deviltail:

[Bitsyncmaster]

FYI:

You should not need to jump the low pressure switch to start charging the system. When you open your can of refrigerant the gas pressure is above 50 PSI. Now the can will get cold pressuring the system that should be sitting at a vacuum so you put the can in a pan of hot water and wait till the can has emptied. Keep the can vertical so only gas is used for charging the system engine running, AC on normal, blower on highest speed, doors open.

If it's really hot when charging your compressor may never cycle at idle RPM which is normal. It all depends on the air flowing over the condenser and evaporator and engine RPM.

You test your low pressure switch operation by reducing the blower speed which will let the system pull the low pressure down to let it cycle. When your driving the higher RPM and more air flow over the condenser normally make the compressor cycle.

[jangell]

Thanks everyone. This weekend I have to replace the water pump, so while I have the belt off I can confirm which ports are which on the compressor by turning it by hand.

So what I'll be doing is:
- Verifying the compressor high/low ports by turning it manually and seeing which port sucks and which port blows, just to be sure.
- Verify compressor mounting
- Verify compressor oil
- Replace the orifice tube and accumulator? Should I bother with neither, one or both?
- Vacuum the system for an hour to make sure it's evacuated
- Turn on the key and jump the low pressure switch just to make sure the compressor works, then plug it back in as normal.
- Put a box fan in front of the radiator
- Turn on the engine
- Fill with 30 oz from the low side with the engine and compressor running. The compressor should start automatically soon after the first can starts being drawn into the system. If not, jump it until the first can is empty?
- Use the warm water trick to get more refrigerant out of the cans.
- Once filled, adjust the low pressure switch for R134a.
- Test the low pressure switch by reducing the blower speed and see if the compressor cycles.

Thanks!

-- Joe

[Ron]

60610

[jangell]

Ah, right — I’ll add that to the list. Thanks!

— Joe

[Rich]

A reference here to a Sanden manual to consider as you look to tear back into it:

You mention the unit is a Sanden SD709. The manual for that model is HERE (http://www.sanden.com/productlibrary/manuals/SD_Service_Guide_Rev_2.pdf)

Among other things there you will see which port is the D (Discharge/high) side and which is the S (Suction/low) side.

Looks like the D and S letters are embossed on the compressor cylinder head assuming the sketch on p.8 applies to this model. If so then these ports are reversed vs the Sanden model that DeLoreans came with. You might get a mirror or camera back there to verify which port is stamped as which on your unit. The rotation test you plan may verify.

The SD709 is listed as a R-12 model, not a R-134a model, in Secs. 1.0 and 2.0 of the manual. Whether that's important or not I don't know.

[jangell]

Great -- thanks, I'll check for those stamps this weekend too.

The Four Seasons 58555 (which cross-refs to the Sanden SD709) is both R12 and R134 compatible, at least according to their spec sheet, so I'm good there.

Thanks!

[David T]

While the compressor may be able to run -12 and -134, if it contains the wrong type oil you will have problems. The safest thing to do is just remove the oil and fill with the proper one for the type refrigerant you choose. Because you can still get -12 you should use it and not -134.

[jangell]

Sounds good. If I remember correctly it came filled with the correct oil for R134, but it won't hurt to drain and refill it.

Spec page, confirming R134a oil and seals: https://www.4s.com/en/ecatalog?part=58555&type=p&search=s

-- Joe

[jangell]

The water pump replacement took longer than expected (partly because I had to remove the Y pipe, forgot to replace the O-rings, and had to remove it again when the valley filled with coolant...), so I didn't get to much of the A/C system yet. It's also going to be in the high 90s this weekend and humid, so I might wait another week before doing the rest of the list.

Mounting: I'm sure the compressor is mounted correctly. The mounts cannot be removed from the compressor body, it only mounts one way, and the drain plug is mounted on the passenger side above the mid level (so not all the way on top, but as on top as it gets for this, it seems).

Oil: I have not checked the oil level yet. I know it came filled from the factor, but now I've filled the system (probably mostly with air) and emptied it, so did I take some significant amount of oil with it? It ran for 10-20 minutes at most, but I don't know if that's enough to circulate a significant amount of oil out of the compressor. Do I need to drain it and refill it, or should I be fine as-is? I can pull it if need be; it's just a bit of a pain (have to take off the belt, remove the air intake on my car, remove the lines, unbolt the compressor), so if I can be lazy I'd prefer that. :) But I'd also like a working A/C system.

Routing/Connections: I took the passenger side hose off of the compressor to try to shine a light in there to read the "S" or "D" on inside when I noticed the giant "S" and "D" printed on the back of the compressor casing itself that I somehow didn't see before. I traced the "S" side hose and confirmed that it connects to condenser, and is in fact the low side. I tried to turn the compressor by hand with the clutch engaged to see if I could feel suction, but I couldn't turn it fast enough for that. I'm thinking of taking the "S" like off, turning the car on, and using a PowerProbe to briefly power the compressor and see if I feel suction, just to confirm that it's turning the right way. However, this is the cross-reference part for a 1989 Eagle Premier, so it seems likely that's already correct.

I checked all the other hose routing and they seem to be fine.

Accumulator: The system is currently filled with air at atmospheric pressure. I didn't get around to replacing the accumulator and orifice tube yet (but I do have them). I assume I should do this before trying to fill it again. Hopefully since they were only put on a year ago they won't be too hard to take off. I was going to try it this morning, but it's already pretty humid and I have to do day-job work, so it'll have to wait.

I also found out that the knob on my manifold set that opens/closes the yellow line seems to be stuck on "open" and never seems to seal closed. Simply closing the low/high knobs should let me work around that problem, and my can side tap has a Schrader valve that should keep the yellow line purged while I switch cans.

I'll report back after testing, but I'd like some opinions on if I need to bother checking the oil. I'm just assuming that the accumulator/orifice need to be replaced at this point unless someone tells me otherwise. I mean, I could just fill it now and see if it works, but I'd kind feel bad about having to vent R134a if it doesn't.

Thanks!

-- Joe

[Bitsyncmaster]

You don't loose much oil doing the evacuation and refill. The question is what kind of oil came in the compressor. I would drain the compressor and add the oil type you want. I would also flush the system but not sure how much oil you now have in the system. Defently change the accumulator right before your ready to fill the system. The accumulator holds a few oz. of oil and being open in these humid days would fill the desiccant with water.

[jangell]

The specs page for the Four Seasons 58555 says that it comes pre-filled with 3 oz of PAG, so I'll leave it at that:


Our products are engineered and tested to provide years of trouble free operation. Backed by over 50 years of mobile a/c experience, fix it once and fix it right with Four Seasons.
New Compressors meet or exceed OE specifications
New Compressors are validated for the equivalent of 100,000 miles
New Compressors come pre-charged with 3 ounces of PAG oil for R134a or R1234yf applications
New Compressors come with direct fit connectors for ease of installation and to help eliminate splicing
New Compressors come with the R12/R134A/1234yf required o-rings /sealing washers to install the compressor
New Compressors are built in a ISO9001:2015 Certified facility. These facilities go through several audits to ensure quality standards in the manufacturing process.

I'll definitely replace the accumulator/orifice before vacuuming and filling it then. We'll see just how hot it is this weekend, but at worst I hope to do it next weekend.

Thanks!

-- Joe

[DMC-81]

Oil: Was the entire system flushed and or brand new when you started? If so, and you're confident that the new compressor was filled with the correct oil amount, then I think you will be good. If not, perhaps it would be prudent to flush the system and drain the compressor and start again.

My system had a blockage of too much oil in the evaporator, a condition called "oil logged". (Not suggesting yours is the same, but just illustrating that too much oil in the wrong place can be a problem.

Because your pressures are out of whack, I would check each component for a blockage before charging it again.you can do this by blowing compressed air through each component.

Accumulator: Yes, you should change the accumulator as the last step before vacuuming it down and recharging. As you may know, it has desiccant inside and can't be flushed or left to atmospheric pressure.

[jangell]

Oil: The system has never (successfully) been filled before, and everything in it is new and set up for R134a, so there's no old oil to worry about.

Accumulator: I was hoping that I'd held it at vacuum successfully for long enough that, but I was pretty sure that this was no longer the case and need to stop being lazy and just replace it. :)

Thanks!

-- Joe

[Bitsyncmaster]

Note a lot of people think holding a vacuum will pull moisture out of desiccant. That is not the case. It takes heat (about 250 deg. F) to remove the moisture from the desiccant. Now if you had an accumulator without any oil in it from being used, you could bake it for an hour or two but that would be very messy if oil was in it.

Some of my electronic components need to be sealed in jars with desiccant until they are soldered onto the circuit board. The reason is the moisture can crack the seal of the plastic case during soldering. So I tried to rejuvenate the desiccant by just holding it at a vacuum for one week and it did nothing. Put it in the oven for one hour at 250 deg and it's like new again.

[jangell]

I wouldn't have thought of heating it to refresh it -- I just figured it was junk and that was that. Although once you get the accumulator out it seems to make more sense to simply replace it, since they're not expensive and you've done all the hard work. I guess if you don't have a replacement handy it makes sense to try to rejuvenate it, though. I admit I'm tempted to keep my old one as a backup and use that trick if I need to swap it out again in a pinch (or if I screw up filling it again :) ).

Having to keep certain electronics components dry before solder is quite interesting -- that's not something I'd come across before.

-- Joe

[Ron]

Mounting: I'm sure the compressor is mounted correctly. The mounts cannot be removed from the compressor body, it only mounts one way, and the drain plug is mounted on the passenger side above the mid level (so not all the way on top, but as on top as it gets for this, it seems).

The mounting is correct if it sits at the same angle as it does on a 1989 Eagle Premier. It will work but you have to look in the manual and follow the steps to check total amount of oil in the system.


Oil: I have not checked the oil level yet. I know it came filled from the factor, but now I've filled the system (probably mostly with air) and emptied it, so did I take some significant amount of oil with it? It ran for 10-20 minutes at most, but I don't know if that's enough to circulate a significant amount of oil out of the compressor. Do I need to drain it and refill it, or should I be fine as-is? I can pull it if need be; it's just a bit of a pain (have to take off the belt, remove the air intake on my car, remove the lines, unbolt the compressor), so if I can be lazy I'd prefer that. :) But I'd also like a working A/C system.
10 minutes at idle is the time required to distribute the oil before measuring it according to the WS Manual.
If "everything in the system is new", note that Sanden shows 6 ounces is typical for total system oil charge for a 508 compressor (stock for D). A D will require more because of the long lines. I would guess 7-8 total. If you didn't change the evaporator and condensor, and you didn't flush the system, then the 3 oz that came with the compressor is probably enough. But, like Dana said, there may be too much, depending on what went wrong to begin with, etc.


Routing/Connections: I took the passenger side hose off of the compressor to try to shine a light in there to read the "S" or "D" on inside when I noticed the giant "S" and "D" printed on the back of the compressor casing itself that I somehow didn't see before. I traced the "S" side hose and confirmed that it connects to condenser, and is in fact the low side.
This confirms that you have the wrong routing.


I tried to turn the compressor by hand with the clutch engaged to see if I could feel suction, but I couldn't turn it fast enough for that. I'm thinking of taking the "S" like off, turning the car on, and using a PowerProbe to briefly power the compressor and see if I feel suction, just to confirm that it's turning the right way.
Virtually all compressors are turned clockwise. It is turning the correct way. "Powering the compressor" doesn't help anything here. Turning the clutch only will make it pump.


I checked all the other hose routing and they seem to be fine.
Can't be fine if the suction is going to the condenser.
And, as mentioned before, it having hot-cold-hot-cold spots indicates you have something wrong concernig routing and/or blockages (oil, hose,?).


Accumulator: ...
I'm just assuming that the accumulator/orifice need to be replaced at this point unless someone tells me otherwise. I mean, I could just fill it now and see if it works, but I'd kind feel bad about having to vent R134a if it doesn't.

Oil: The system has never (successfully) been filled before, and everything in it is new and set up for R134a, so there's no old oil to worry about.
Accumulator: I was hoping that I'd held it at vacuum successfully for long enough that, but I was pretty sure that this was no longer the case and need to stop being lazy and just replace it.I would not install the new accumulator until I had the system cooling...and oil checked depending on whether it is ALL new or not (see "OIL:" above).

The accumulator is shipped with an inert gas and its caps should not be removed until you are 100% ready to connect it up. Minutes and seconds matter. Also, the desiccant in the accumulator can not be dried out by placing it under a vacuum. It binds with moisture and it takes relatively high heat to release it. Heating it to the required temp will usually destroy the desiccant's container.

Edit: Sorry for duplicate info ( Dave beat me to the last part;-)

[jangell]

The mounting is correct if it sits at the same angle as it does on a 1989 Eagle Premier. It will work but you have to look in the manual and follow the steps to check total amount of oil in the system.

AFAIK it does, but I never had a complete Premier/Monaco to look at, so I don't know for sure. I just know that the compressor is correct for a Premier according to the Four Seasons lookup site.


10 minutes at idle is the time required to distribute the oil before measuring it according to the WS Manual.
If "everything in the system is new", note that Sanden shows 6 ounces is typical for total system oil charge for a 508 compressor (stock for D). A D will require more because of the long lines. I would guess 7-8 total. If you didn't change the evaporator and condensor, and you didn't flush the system, then the 3 oz that came with the compressor is probably enough. But, like Dana said, there may be too much, depending on what went wrong to begin with, etc.

I was wondering about the 3 oz thing. A quick video I found today showed refilling a Sanded-style condenser with 6 oz of PAG, like you said. I did change the evaporator and condenser (and everything else), so based on what you've said that 3 oz is probably not enough. I have a can of full PAG that I haven't used yet.


This confirms that you have the wrong routing.

I am constantly getting which side is which turned around in my head. I need to print that diagram and stick it to the wall or something.

Here's a bad picture of the back of the compressor, showing the "S" and "D" connections. The disconnected line is the one that I originally thought was the high side line, then figured was the low side based on the readings from the gauges. Turns out it's the high side line, but not the high side of the compressor.

60709

I just went out and put a loose zip tie on one of the lines and slid it down from the compressor to the frame to make sure I absolutely know which hose is which. The line from the S side of the compressor is definitely going down the driver's side of the frame towards the condenser.

Now the question is how to swap them. I'm hoping I can just switch the hoses at the compressor (assuming the connections are the same size), but I think one of them has a threaded connector while the other doesn't (it's held on by a bracket, like in the original setup), and that concerns me a bit. I'm not going to be able to go back out and take things off today (way too hot and humid), but it'll be cooler tomorrow so I'll check it then. It would be so very convenient if I could just switch them.

Looking at the parts manual diagram https://store.delorean.com/c-303-7-2-0-refrigerative-system.aspx I have the routing physically correct, except for the fact that these are not the S and D ports on my condenser, which makes it incorrect.

This is the thread where I asked for recommendations for the compressor, BTW: http://dmctalk.org/showthread.php?16183-3-0L-R134-compressor-recommendations. I'll note that Farrar's picture of an Eagle compressor installed shows the low side on the passenger side, just like on my compressor, but I have the hoses connected wrong. And the oil drain plug is in the same place, so it seems I have it mounted correctly. :)


Virtually all compressors are turned clockwise. It is turning the correct way. "Powering the compressor" doesn't help anything here. Turning the clutch only will make it pump.

I wasn't sure if I could feel the suction by disconnecting the line turning it and seeing if it sucked or blew while the clutch was engaged. That was the theory, anyway. Assuming the ports are labeled correctly on the back of the case, I don't need to do this test.



Can't be fine if the suction is going to the condenser.
And, as mentioned before, it having hot-cold-hot-cold spots indicates you have something wrong concernig routing and/or blockages (oil, hose,?).

I would not install the new accumulator until I had the system cooling...and oil checked depending on whether it is ALL new or not (see "OIL:" above).

That sounds like a plan to me. This weekend (weather permitting) I'll check the oil in the compressor, add to it as needed, fix the hose routing, and then fill the system again and see if I actually get cold air. Only after it works will I replace the accumulator.


The accumulator is shipped with an inert gas and its caps should not be removed until you are 100% ready to connect it up. Minutes and seconds matter. Also, the desiccant in the accumulator can not be dried out by placing it under a vacuum. It binds with moisture and it takes relatively high heat to release it. Heating it to the required temp will destroy the desiccant's container.

Edit:Sorry for duplicate info ( Dave beat me to the last part;-)

Got it -- Dave's comment was more about his electronics desiccant, not about the accumulator. I'll consider the old one junk then.

I have not and will not remove the caps on the accumulator until it's time to install and fill it. I knew this before, but it's good to have it reinforced. Thanks!

-- Joe

[Bitsyncmaster]

Just remember the S stands for suction and is routed to the low (gas) side which is on the passenger side of our car. The D is the discharge side (high side) and is routed to the condenser via the drivers side on out car.

[Ron]

I was wondering about the 3 oz thing. A quick video I found today showed refilling a Sanded-style condenser with 6 oz of PAG, like you said. I did change the evaporator and condenser (and everything else), so based on what you've said that 3 oz is probably not enough. I have a can of full PAG that I haven't used yet.
I'd add 3 oz. If you need more later, you can put it in with a charge can.


I am constantly getting which side is which turned around in my head. I need to print that diagram and stick it to the wall or something.
Maybe this will help. The flow: compressor "D"=High Side -> condenser -> orifice -> evaporator -> accumulator -> compressor "S"=Low Side


Here's a bad picture of the back of the compressor, showing the "S" and "D" connections. The disconnected line is the one that I originally thought was the high side line, then figured was the low side based on the readings from the gauges. Turns out it's the high side line, but not the high side of the compressor.

60709
No, that is the high side of the compressor that is hooked up in the pic. What hose you have hooked to it I can not tell. That is the high side gauge hose hooked to it, of course, assuming the other end is correctly hooked to the gauge manifold.....


I just went out and put a loose zip tie on one of the lines and slid it down from the compressor to the frame to make sure I absolutely know which hose is which. The line from the S side of the compressor is definitely going down the driver's side of the frame towards the condenser.
That is wrong. "S" comes from the Accumulator.


Now the question is how to swap them. I'm hoping I can just switch the hoses at the compressor (assuming the connections are the same size), but I think one of them has a threaded connector while the other doesn't (it's held on by a bracket, like in the original setup), and that concerns me a bit. I'm not going to be able to go back out and take things off today (way too hot and humid), but it'll be cooler tomorrow so I'll check it then. It would be so very convenient if I could just switch them.

Looking at the parts manual diagram https://store.delorean.com/c-303-7-2-0-refrigerative-system.aspx I have the routing physically correct, except for the fact that these are not the S and D ports on my condenser, which makes it incorrect.

This is the thread where I asked for recommendations for the compressor, BTW: http://dmctalk.org/showthread.php?16183-3-0L-R134-compressor-recommendations. I'll note that Farrar's picture of an Eagle compressor installed shows the low side on the passenger side, just like on my compressor, but I have the hoses connected wrong. And the oil drain plug is in the same place, so it seems I have it mounted correctly. :)

You said before that Farrar's was "similar", iirc. A lot of those colored caps can fit either side, and the back plates can be different on the same model as mentioned....I think you should forget everything and stick to the chart.

Put whichever hose that goes down to the condenser on the port labeled "D", the high side, and go from there. (Same for Red gauge hose, assuming it is correct on the gauge's manifold...) I like your pull tie trick! Use it to confirm the rest, especially in the nest up front (no matter what ;-).


I wasn't sure if I could feel the suction by disconnecting the line turning it and seeing if it sucked or blew while the clutch was engaged. That was the theory, anyway. Assuming the ports are labeled correctly on the back of the case, I don't need to do this test.

:thumbup:

YW!

[jangell]

I'd add 3 oz. If you need more later, you can put it in with a charge can.

Sounds good


Maybe this will help. The flow: compressor "D"=High Side -> condenser -> orifice -> evaporator -> accumulator -> compressor "S"=Low Side

Thanks -- I'll copy that down for reference. I'm also starting to think "D" for "driver's side", but I know that's very specific to our cars and not a general rule, so I shouldn't get used to it.


No, that is the high side of the compressor that is hooked up in the pic. What hose you have hooked to it I can not tell. That is the high side gauge hose hooked to it, of course, assuming the other end is correctly hooked to the gauge manifold.....

Yup -- the high side gauge hose is hooked to hose in the discharge port, but that hose goes to the accumulator, not the condenser, which is wrong. And once it's moved to the suction port, the blue (low) gauge hose should be connected to it.


That is wrong. "S" comes from the Accumulator.

Right -- sorry, I meant that's how it's connected at the moment, and is indeed wrong.


You said before that Farrar's was "similar", iirc. A lot of those colored caps can fit either side, and the back plates can be different on the same model as mentioned....I think you should forget everything and stick to the chart.

Good point. I'll stick to the chart.


Put whichever hose that goes down to the condenser on the port labeled "D", the high side, and go from there. (Same for Red gauge hose, assuming it is correct on the gauge's manifold...) I like your pull tie trick! Use it to confirm the rest, especially in the nest up front (no matter what ;-).

Thanks for your patience and help with this -- I'm almost there... pretty sure, anyway. ;)

-- Joe

[Ron]

By Jove, I think you've got it!:)

Don't cheat using the pull ties. :deviltail:

[jangell]

I should just stick blue and red pull ties (or electrical tape) at intervals down the appropriate lines so I never mix them up again. :)

-- Joe

[Bitsyncmaster]

If your hoses can't be swapped, maybe if you pull the back plate and rotate it 180 deg. (if possible) it may reverse the hose connections.

[David T]

Some more tips to confuse you;
Make VERY sure the pressure hose (discharge hose) is SECURELY attached to the frame where it passes by the steering shaft. The bolt can rip the hose apart if it touches.
Make sure the hoses do not put stress on the evap or condenser fittings. They are aluminum and will fracture. No twists or pulling.
The oil drain for the compressor is supposed to be on the bottom.
You can "regenerate" an accumulator with heat and vacuum but if it is contaminated with old, acidic oil (or the wrong type oil) you cannot clean it. Best to replace it after you have done your pressure testing and before your final evacuation and charging.
D is for Discharge. It is the port that the high pressure hot gas comes out of to go to the condenser coil to turn into a warm liquid. S is for Suction and is the port the warm low pressure gas enters the compressor to be turned into a high pressure, hot gas.
The discharge hose runs along the left, driver's side,to the condenser.
If your manifold gauge set is not working correctly get it fixed or get another. It is dangerous to use equipment on high pressures that is faulty. The valves MUST seal properly to the yellow hose (center port). Always verify the gauges read 0 before connecting. Adjust them if necessary. Any good gauge set has gauges that can be zeroed. Blue to the suction (low pressure) side and red to the discharge (high pressure) side. Yellow to your charging can and/or vacuum pump.
On most A/C systems the high pressure port is AFTER the condenser coil. On Deloreans they put it right on the discharge of the compressor. You must remember that because your reading will be very high because the gas has not been cooled so evaluate your readings accordingly by the temperature/pressure chart for the refrigerant you are using.
You should pull a vacuum of at least 50 microns and hold it for 30 minutes to remove all air and moisture. 30 is even better.

[jangell]

Success!

I easily swapped the hoses at the compressor (they're not threaded or anything like that, and I don't know why I thought they might be; they just press into place with O-rings and that center bolt/plate arrangement), replaced the accumulator and orifice tube (the latter was actually stuck in the end of the hose and the plastic case had a break, so that didn't help), vacuumed it for over an hour, and filled it with R-134a.

I took it for a test drive to pick up a vent thermometer after I lost the one I bought a few weeks ago for this purpose. On the way home, I read about 50 F for the center-ish vent (my vents are in the knee pads), but the external temp sensor on my car is reading 100 F, so I think that's pretty good. I'll have to see what it's like on an 80 degree day.

There is more to do, though:
- I added ~3 oz of PAG 100 to the compressor, which itself came pre-filled with 3 oz of PAG 100. It seems to be working fine.
- I haven't adjusted the low pressure switch for R134a yet.
- I need to rig up some kind of A/C high idle though MegaSquirt. I stalled a couple of times when stopping, and even had some trouble restarting the car with the A/C engaged, so I need to look at my idle settings. I have issues with low RPMs when coming to a stop anyway, so this isn't unique to the A/C -- it just made it worse.
- I aimed a box fan on high at the radiator while filling.

One thing I'm trying to figure out, though, is that I only put in about two 12 oz cans. The pressures seemed ok, with the high at about 275 on this 90-100 degree day, and the A/C seems to be blowing cold enough. However, I just re-read Dave's post about how the location of the high side port on the DMC means that the reading should be higher than what most charts show. I was filling with the engine at 900-1000 RPM. While the compressor cycled just fine up until the end of that second can (at which point it just stayed on), some reading afterwards suggested that I should have tried a higher RPM so that the compressor would compress more, and the pressures would go higher.

To be honest, though, at the moment I'm just happy that it's working at all, but I'm guessing that I don't have enough refrigerant in it and I need to fix that.

Thanks!

-- Joe

[WHO1DMC]

Did you get the car up to 50-55 MPH? Doing this for say 5 to 10 miles will give the orifice tube a good chance to seat in. You might feel the difference when it does. I know I did.

My $0.02

David B.

[Ron]

One thing I'm trying to figure out, though, is that I only put in about two 12 oz cans. The pressures seemed ok, with the high at about 275 on this 90-100 degree day, and the A/C seems to be blowing cold enough. However, I just re-read Dave's post about how the location of the high side port on the DMC means that the reading should be higher than what most charts show. I was filling with the engine at 900-1000 RPM. While the compressor cycled just fine up until the end of that second can (at which point it just stayed on), some reading afterwards suggested that I should have tried a higher RPM so that the compressor would compress more, and the pressures would go higher.

To be honest, though, at the moment I'm just happy that it's working at all, but I'm guessing that I don't have enough refrigerant in it and I need to fix that.

Thanks!

-- JoeCongrats!!!
Now finish up :smile::
You have 24oz 134a in it now. You need 31.6oz total, as David said in post #2, so it needs 7.6oz (~215 grams).
Assuming you don't have the scales and tap can that normally goes with the gauges, you can still install the correct amount:
Get an inexpensive scale (<$15 at Walmart, etc.) that can measure in 1/10oz (or grams).
Weigh and record (Varies by brand!):
12oz can of 134a (Ex: 32oz)
Recharge hose (Ex: 34oz)
Add together (Ex: 32 + 34 = 66oz)

The new can is holding (12oz - 7.6oz) = 4.4oz (125 grams) too much refrigerant...
Attach the can to the recharge hose and place on scales.
Bleed off until it weighs 4.4oz less. (Ex: 66 - 4.4 = 61.6oz (1746 grams)).
[Practice placing the assembly where it will stay w/o touching it while it bleeds off first!]
Shut the recharge hose's valve immediately.
The correct (remaining) charge is in the can.

Connect HIGH side of gauges with all valves shut!
Start the engine, let idle -- Turn the air on max cool & max fan.
Keep one eye on the high side gauge at all times for safety (see gauge manual)!
Keeping the can upright, connect the recharge hose to the LOW side.
Be patient until the can is totally empty.
(If you keep shaking the can you should notice it get cold then go back to ~normal when it is empty.*)
Disconnect the recharge hose assembly.
The total charge should be correct.

Pressure Check:
Connect the LOW side of the gauges.
Adjust idle to ~1500 RPM.
Wait until engine is fully warm, if needed.
Compare the readings with the following WS Manual (R12) chart below.
Make sure that you take both readings when the compressor turns OFF!!!
Your pressures will be higher since you are using 134a!

Since you are using 134a, you need to calculate the correct(ed) target pressure for the high side:
Add 40°F to Ambient temp then look the value up in a conversion chart (Conversion Chart, Details HERE (http://dmctalk.org/showthread.php?7921-AC-Pressure-Charts-Reading-Gauges-(R12-and-Retrofit)&p=116745&viewfull=1#post116745)).
(Ex: For 90F ambient. 90 + 40 = 130F, which corresponds with 198.9psi in the chart. So expect ~189 to 235psi+)
Don't push your luck in 100F+ climates -- Adjust the pressure switch so there is no chance of it getting over 300psi.

60741

Wear safety goggles. Don't pollute. And, above all, don't tell the cook if you borrowed their scales!