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

[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:

DMC_AC_Readings.jpg

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.

[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]

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

[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
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:

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