weird r134a fill issue

[mowpow]

Looks like the PO changed my system to r134a. It's not blowing cold and compressor is cycling every 5 seconds. Bought a gauge kit and low side is about 10 psi at rest. To fill I jumped the compressor and turned the AC on full blast. When I opened the can the low needle pegged and i can't get it to lower. I sealed the can and left it for a while with the car off and its still pegged. Did I trigger some safety valve or something? What should I do? I don't want to take the low hose off since I don't want to spray refrig everywhere.

Thanks
Jake

[NightFlyer]

Looks like the PO changed my system to r134a. It's not blowing cold and compressor is cycling every 5 seconds. Bought a gauge kit and low side is about 10 psi at rest. To fill I jumped the compressor and turned the AC on full blast. When I opened the can the low needle pegged and i can't get it to lower. I sealed the can and left it for a while with the car off and its still pegged. Did I trigger some safety valve or something? What should I do? I don't want to take the low hose off since I don't want to spray refrig everywhere.

Thanks
Jake

Not sure what the problem is - the pressure naturally increases during charging.

As long as you didn't remove the schrader valve cores (no reason to except to make charging go faster) from the service port and there's some kind of shut off on your can tap or gauge set, there should be nothing preventing you from removing the hose normally.

[mowpow]

I didn't mess with the valves so those should be ok. I wonder if the valve didn't open, I will disconnect the line and try again. Since my compressor runs a little is it still necessary to jump it while filling?

[NightFlyer]

I didn't mess with the valves so those should be ok. I wonder if the valve didn't open, I will disconnect the line and try again. Since my compressor runs a little is it still necessary to jump it while filling?

Possible that you 1) didn't have the hoses on tight enough to depress the shrader valve and thus your gauge is only reading the can pressure, or 2) you had the hoses on too tight and the core depressor in the hose fitting is blocking flow from the hose and into the service port (I had this happen to me recently). If your hoses are anything like mine are, it's a delicate balance between not tight enough and too tight, requiring experimentation to get just right, unfortunately...

As such, you might lose whatever refrigerant is in the charge hoses to atmosphere upon removal of them, but nothing more than that.

I didn't jump my compressor at all, but I started with a vacuum on the system. As your compressor is engaging some, it's not necessary to jump the compressor. Just place your can of refrigerant in a pot of hot water to charge properly (as a gas, and not as a liquid - as such will ruin the compressor), otherwise it will take up to an hour to fully charge the system (ask me how I know).

Best luck!

[Rich_NYS]

If I follow this correctly, it seems like the 134 isn't going in....is that right?

When we charged mine at DCS, I think we had a similar issue. Bill & Steve pointed out that some of the conversion adapters are kinda cheap and malfunction easily. I replaced the adapter and we were then able to charge the system.

[NightFlyer]

If I follow this correctly, it seems like the 134 isn't going in....is that right?

When we charged mine at DCS, I think we had a similar issue. Bill & Steve pointed out that some of the conversion adapters are kinda cheap and malfunction easily. I replaced the adapter and we were then able to charge the system.

If you stick with the R-12 service ports, 1/4" SAE (male w / tapered threads), and not put adapters on them, then there's no adapter to worry about messing things up for you.

I like keeping it simple and original :smile:

But yes, that's a GREAT point - any adapters that you have on your service ports may not be functioning very well. But if all you have are hoses for R-134a connections, with 1/2" ACME fittings, then you'll have to use some type of an adapter either on the port end or on the hose end.

Note that if you're using an adapter that's permanently mounted to the service port, you want to completely remove the stock port schrader valve core, and only use the schrader valve core that's within the adapter that you're using.

[mowpow]

Hmm, I'm starting to think you are right with the valve being bad. So I'm getting readings fine but the minute I open the low side knob to start putting in frig, even with the frig can closed, it's like the valve seals off, almost as if it's one way or something. To swap the valve, do I have to evacuate the system?

[NightFlyer]

Hmm, I'm starting to think you are right with the valve being bad. So I'm getting readings fine but the minute I open the low side knob to start putting in frig, even with the frig can closed, it's like the valve seals off, almost as if it's one way or something. To swap the valve, do I have to evacuate the system?

If you're talking about the schrader valve on the service port - yes, you have to depressurize the system to remove and replace it UNLESS you have a special tool like this (which usually costs around $35+):


https://www.youtube.com/watch?v=M4ZMVcDvJzU

[NightFlyer]

Another thing that you may want to check is the rubber seals within the hose fittings - they sometimes become dislodged and will prevent proper flow in and out of the hose.

Also make sure that you have the hoses hooked up correctly - the end with the core depressor in it needs to connect to the service port, while the wide open end connects to your manifold gauge set.

[mowpow]

Do these look like retrofit fittings?


http://mowpow.com/wp-content/uploads/2014/06/acvalves.jpg

[David T]

First of all if you have 10 psi at rest the compressor should not cycle AT ALL! Something is wrong if it can run below around 25 psi. At rest you should have 60-70 psi (even more with -134). You never said what your high side pressure is. I am guessing but you probably have a lot of air in the system. I would vacuum out (evacuate) the system and start all over. You must also check that the low and high pressure switches are wired and operating correctly.

[Ron]

Do these look like retrofit fittings?

Looks like R-134a fittings.

[DMCMW Dave]

Do these look like retrofit fittings?

]

Those are crap fittings. Get steel ones with the schraders in them, not just "extenders". Remove the ones in the R12 fittings. If the system is really 10 PSI it is effectively empty anyway. You will need to evacuate it, so you may as well put the right fittings on there.

The can you are using probably isn't pressing the center pin enough to hit the Schrader.

[NightFlyer]

Yep - those are definitely R-134a adapters.

And this is exactly why I'm a proponent of just using the stock R-12 service ports, provided you either have r-12 hoses/fittings or an adapter that will work on your R-134a hose fittings, as opposed to the service ports. One less thing to go wrong and have to worry about, but that's just my honest opinion.

If you want to keep with adapters on the service ports, then do as Dave S suggested and get the high quality ones with their own schrader valves in them (as opposed to just being mere extensions like you currently have). If you do this, don't forget to remove the stock schrader valve cores from the service ports before installing the new adapters.

As you'll be removing (and changing) your adapters, you'll have to depressurize/evacuate the system, thus you'll want to vacuum it down and then start over with a completely fresh full charge of R-134a, as others here have suggested.

A full charge of R-134a requires 30oz of refrigerant.

Best luck :thumbup:

[Rich_NYS]

Do these look like retrofit fittings?

Yes, the one on the left looks like the same type of adapter I had trouble with. It screws on over the existing R-12 valve and essentially, the bottom of the "pin" of the valve in the adpater pushes against the top "pin" of the one it's screwed onto.




Hmm, I'm starting to think you are right with the valve being bad. So I'm getting readings fine but the minute I open the low side knob to start putting in frig, even with the frig can closed, it's like the valve seals off, almost as if it's one way or something. To swap the valve, do I have to evacuate the system?

If it is an adapter screwed onto an original valve, you should be able to remove the [R-134a] adapter to reveal the original [R-12] valve without evacuating. You might even be able to see if there's something visibly wrong with the adapter that prevents it from doing the job. If you're first wanting to confirm/deny the adapter as the issue, you can easily try another. The elCheapo ones are about $12.

[DMCMW Dave]

If it is an adapter screwed onto an original valve, you should be able to remove the [R-134a] adapter to reveal the original [R-12] valve without evacuating. You might even be able to see if there's something visibly wrong with the adapter that prevents it from doing the job. If you're first wanting to confirm/deny the adapter as the issue, you can easily try another. The elCheapo ones are about $12.

Funny thing is that the good ones don't cost any more than that. They are just hard to find.

[mowpow]

Thanks guys great info. The high side shows about 100 at rest and cycles between 90 and 150 as the compressor cycles. So can I just remove the extenders or is there a risk of the r12 fittings coming off too? I wonder if I have higher pressure on the low side but I am only getting a partial reading because the valve isn't getting fully depressed?

[NightFlyer]

Thanks guys great info. The high side shows about 100 at rest and cycles between 90 and 150 as the compressor cycles. So can I just remove the extenders or is there a risk of the r12 fittings coming off too? I wonder if I have higher pressure on the low side but I am only getting a partial reading because the valve isn't getting fully depressed?

Yeah, you can go ahead and remove the extenders/adapters that you have on there - the schrader valve cores in the service ports shouldn't come off when do this (unless they're stripped).

The fact that the compressor is running suggests that you do indeed have higher pressure on the low side than what you're currently reading - the adapter on the low side isn't opening up the valve enough to give you a good reading. It's also possible that the adapter on the low side has so screwed up the underlying schrader valve core in the service port that it's actually leaking around the schrader valve.

Get those extenders/adapters off and decide how you want to proceed from there - fit new proper adapters with their own schrader valve cores (requiring the elimination of the actual service port schrader valve cores), or use a removable adapter on your hose fittings and retain the bare stock service ports with their schrader valve cores (although it still might be a good idea to change out those cores for new ones, should you decide to go that route).

Best luck :thumbup:

[mowpow]

Cool, thanks for all the great info, i definitely learned a lot! I have hoses for R12 so after this whole experience I think I'm going to take your advice and keep the R12 fittings, less to go wrong LOL. Will just have to make a cap or something that says R134a so no one comes along thinking they are going to be R12 in there haha.

[David T]

Thanks guys great info. The high side shows about 100 at rest and cycles between 90 and 150 as the compressor cycles. So can I just remove the extenders or is there a risk of the r12 fittings coming off too? I wonder if I have higher pressure on the low side but I am only getting a partial reading because the valve isn't getting fully depressed?

If you have 150 on the high side and 10 on the low side you have air in the system. When converting to -134 you are supposed to either change the fittings or use adapters so no one accidentally puts -12 in anymore. There is also supposed to be a new label indicating the conversion and the correct amount of fill. Why will it run at all, you have not answered that.

[NightFlyer]

Cool, thanks for all the great info, i definitely learned a lot! I have hoses for R12 so after this whole experience I think I'm going to take your advice and keep the R12 fittings, less to go wrong LOL. Will just have to make a cap or something that says R134a so no one comes along thinking they are going to be R12 in there haha.

Good choice! :thumbup:

[djdogbone]

The low pressure switch has an adjustment screw on top. Adjust it clockwise will raise th cycle pressure on the low side. Keep it hooked up to the gauges and adjust.

Low side should trigger 20-23, high should stop at 40 I think.

[Ron]

Yeah, you can go ahead and remove the extenders/adapters that you have on there - the schrader valve cores in the service ports shouldn't come off when do this (unless they're stripped).


$.02

Be careful...Don't assume that the schrader valve(s) are still there.

[NightFlyer]

$.02

Be careful...Don't assume that the schrader valve(s) are still there.

Always a good point.

But if you look at his photo, you'll note that he only had extending adapters on the ports, thus if the original schrader valves weren't there, there would have been nothing holding the contents within the system or permitting it to pressurize, and also his compressor wouldn't have worked at all without jumping it. All things considered, it was pretty safe to say that they were definitely there in this case - whether or not they leaked is precisely why it was suggested that he change them out (either in the stock ports or with new adapters that have their own built in schrader valves) before going further with any kind of vacuuming/charging.

[Ron]

Always a good point.

But if you look at his photo, you'll note that he only had extending adapters on the ports, thus if the original schrader valves weren't there, there would have been nothing holding the contents within the system or permitting it to pressurize, and also his compressor wouldn't have worked at all without jumping it. All things considered, it was pretty safe to say that they were definitely there in this case - whether or not they leaked is precisely why it was suggested that he change them out (either in the stock ports or with new adapters that have their own built in schrader valves) before going further with any kind of vacuuming/charging.

Assuming that we were looking at a pic of his current setup.., the one on the left looked like several I've seen with a valve...Looking again, I can't even see if there is anything in either, or not.
"Extending" ??? Anywho, some adapters have a valve and a pusher, so you can't tell w/o removing it.

=====

+1 on install good converters and evacuate...

[mowpow]

Quick update on this. I went to remove the low side and heard a hissing when unscrewing it so looks like the valve portion underneath was removed. I can see that the adapter has some corrosion so I think the valve is bad thus won't let the refrig in. I'm going to shop around for a new one to put on. Now that I see the corrosion I'm going with David T's plan and evacuate the system, flush, then refill.

The compressor seems OK as does the wiring, the compressor won't come on now that I let some of the pressure out. Now if I can just get the blower speed 4 to work, but that's another story heh.

Jake

[Ron]

Quick update on this. I went to remove the low side and heard a hissing when unscrewing it so looks like the valve portion underneath was removed. ...or its stem was bent by the crappy "adapter".

[NightFlyer]

Quick update on this. I went to remove the low side and heard a hissing when unscrewing it so looks like the valve portion underneath was removed. I can see that the adapter has some corrosion so I think the valve is bad thus won't let the refrig in. I'm going to shop around for a new one to put on. Now that I see the corrosion I'm going with David T's plan and evacuate the system, flush, then refill.

The compressor seems OK as does the wiring, the compressor won't come on now that I let some of the pressure out. Now if I can just get the blower speed 4 to work, but that's another story heh.

Jake

If you have r-12 hose fittings, you could just put some new schrader cores in the stock service ports and ditch having any kind of adapter atop of them - one less joint to worry about leaking, but that's just MHO.

When you do your flush, be sure to go from the low side to the high side (backflushing). As far as a flushing agent is concerned, mineral spirits and lacquer thinner are the two most commonly used. After flushing, when you're attempting to blow the remainder of your flushing agent out of the system with compressed air, start by back blowing until you're only getting air, then forward blow (high to low) until you're only getting air. Vacuum the system for a good 40 minutes (both sides), charge it (low side only), and you'll be back in action in no time flat :thumbup:

[Ron]

"Flush"???

[NightFlyer]

"Flush"???

Although no one suggested that a flush of the system was necessary, the OP stated that he was going to flush the system:

"Now that I see the corrosion I'm going with David T's plan and evacuate the system, flush, then refill."

http://dmctalk.org/showthread.php?10001-weird-r134a-fill-issue&p=148448&viewfull=1#post148448

But you're right - I think he meant to say 'vacuum' in place of where he said 'flush.'

FYI - A full recharge of R-134a is 30oz.

[alexwolf1216]

Yes forgive my terminology. Im a newbie :)

[NightFlyer]

Yes forgive my terminology. Im a newbie :)

Whoa - OK, hold the phone, this is starting to get confusing.

Alexwolf1216 - you're confusing your a/c thread with mowpow's a/c thread. Mowpow's a/c was already converted, thus he really doesn't need to flush unless he wants to (it's not a bad idea to flush every so often as preventative maintenance to prevent the oil from clogging passages and the orifice from getting plugged up - every 6 years is a good pattern to follow if you're still running all original components).

As you were uncertain as to what is currently in your system, you definitely want to include a compressor drain, a full backflush of the system, and replacement of the system oil, in addition to vacuuming and recharging.

[mowpow]

Replaced the valve in the low side and recharged with 13oz and now the compressor is cycling normally and I am getting cold air, whoohoo! Thanks for all the help.

[NightFlyer]

Replaced the valve in the low side and recharged with 13oz and now the compressor is cycling normally and I am getting cold air, whoohoo! Thanks for all the help.

SWEET, or should that be COOL :biggrin:

[Ron]

FYI - A full recharge of R-134a is 30oz.
Last DMC service bulletin I saw said R12 was reduced from 2.75 lbs to 2.2 lbs.
2.2 minus 10% (recommended reduction for 134a conversion) = 1.98
1.98 lbs x 16 = 31.68 Oz

[Ron]

Replaced the valve in the low side and recharged with 13oz and now the compressor is cycling normally and I am getting cold air, whoohoo! Thanks for all the help.
GREAT!!!

So was the valve missing, bent, or ??

[NightFlyer]

Last DMC service bulletin I saw said R12 was reduced from 2.75 lbs to 2.2 lbs.
2.2 minus 10% (recommended reduction for 134a conversion) = 1.98
1.98 lbs x 16 = 31.68 Oz

Where does this 10% come from? I'm basing it off of molecular weight.

R-12 = 120.91 g/mol
R-134a = 102.03 g/mol

102.03/120.91 = .844

.844 x 2.2 lbs = 1.86 lbs

1.86 lbs x 16 oz = 29.71 oz

I rounded it to 30 oz.

Your calculation is only 1.68 oz off mine, thus where's the issue???

[NightFlyer]

GREAT!!!

So was the valve missing, bent, or ??

He stated that it was corroded.

[Ron]

Where does this 10% come from? I'm basing it off of molecular weight.
R-12 = 120.91 g/mol
R-134a = 102.03 g/mol

102.03/120.91 = .844

.844 x 2.2 lbs = 1.86 lbs

1.86 lbs x 16 oz = 29.71 oz

I rounded it to 30 oz.

Your calculation is only 1.68 oz off mine, thus where's the issue???

As I said, there is a 10% recommended reduction in charge when converting from R-12 to 134a -- It is in the documentation with every kit I have ever seen...because of the higher pressures when using 134a.

Simple arithmetic gives the same answer: 31.68 - 30.00 = 1.68 :p

DMC reduced the charge to 2.2 to eliminate damage to the compressors (knocking), not to improve performance.
1.68/31.68 = 0.05303
So, I guess the issue is that 3.0 would be reducing the system charge, for a system that has already be reduced below its optimum performance due to mechanical limits, yet another ~5.3%, losing even more performance.
(The pressures are not the same/linear, so 5% is even more significant here....)

[Ron]

^^^ I meant to say "30 would be reducing", not "3.0 ..." ^^^



He stated that it was corroded.
No, he said the adapter had some corrosion. And that "it looked like" the valve underneath was removed -- I was just curious to know if it was in fact removed before he "replaced it".
(FWIW- We are talking about the valve and basics you so eloquently lectured me about... ;-)

[Barney10186]

lmao yeah rich i threw that adaptor away when i got home. guess it was a one time use only deal! i evac'd mine and charged it once with it, then you tried it and nothing ha. but yeah my ten cents...