AC Compressor

[Charles W.]

Back trying to get the AC working on my '72.When I bought the car it did not have the ACsystem installed.I installed all componentsand here is what I've got: reconditioned POA valve (reconditioned by that company in Florida)calibrated for R12, new evaporator, new expansion valve, new drier, new hoses,original condenser and an original Frigidaire compressor with an unknownhistory. The compressor came with the car and looks like it might have been reconditioned. A mechanic for many years from thelocal GM dealership came over today and charged the system with R12.The system didn't want to take a full charge,could not get the temp below 62, and the compressor was sweating.A good amount of condensation had formed onthe compressor.The mechanic said hethought the compressor was bad.
I don't have the readings from the gauges but would likeothers opinion regarding the compressor sweating.
Secondly, if the compressor is bad, I would likeinput/recommendations for a replacement or rebuild.Are there competent rebuilders out there? Thecorvette parts suppliers have new A6 compressors for about$400 and reconditioned ones for $300.Are these replacements reliable and worth the price?I don't plan to show the car but always tryto keep it as original as possible, but I'm open to a more modern and efficientcompressor that will bolt up without any modifications.
Thanks for your input.
Chuck

[Keith B.]

Re: AC Compressor

Find a local shop that rebuilds them. They were used in all GM cars and trucks until 81 and most big trucks and farm tractors until the mid 90's. There should be plenty of local shops that can rebuild them for you. No need to send them out

[Tom L.]

Re: AC Compressor

Was the charge weighed in or added while observing pressures? Both ways can work but weighing the charge is the only way to know it's correct when troubleshooting a system. Before moving forward it would be wise to know what pressures the system is operating at and check superheat and sub cooling. With that information it would be pretty easy to determine that it's the compressor or perhaps an expansion valve that is stuck open. Might be worth a trip back to the shop before you just start changing parts. Good luck!!

[Domenic T.]

Re: AC Compressor

Charles,
What pressure did you read on the high side vs the low side?

DOM

[Charles W.]

Re: AC Compressor

Sorry for not responding sooner.I was waiting for new AC manifold gauges toarrive.I'm fairly confident that thesystem in fully charged and might be over charged.Today with temperature at about 85 and fairlyhigh humidity, I get a low pressurereading of 65 and high pressure reading of 160 idling at 1500 RPM .The site glass is foamy.Systemnot cooling??

[Jim T.]

Re: AC Compressor

Charles how is your system since your last post? I read that you installed a new expansion valve. If the expansion valve is like the one on my 1970 Corvette the supply line from the condensor to the expansion valve requires the liquid refrigerant to pass through a small filter screen. From experience if the filter screen becomes blocked or partially blocked your evaporator will suffer. Since your condenser was not changed it could of had something in it that could block a strong supply of refrigerant to enter the expansion valve a 100%. I realize that to check the screen in the expansion valve your refrigerant will have to be recovered followed by a vacuum pull.

[Charles W.]

Re: AC Compressor

Jim, thanks for the response. I've done some analysis but I'm still having the same problems. I agree with you, I think the problem might be the expansion valve. I have found a shop that still works on the R12 systems who seems knowledgeable. I have an appointment with him a couple weeks out.

[Jim T.]

Re: AC Compressor

Charles you mentioned getting another compressor. Looking at Auto Zone for a compressor for my 1970 which is the same as your 1972 they have a few compressors to select from. The cheapest is a remanufactured A6 with clutch for $134.99. They have new A6 with clutch for $260.77. Not a A6 but another new compressor that appears will bolt on like your 72's. Did not know there are replacements like this.

[Mark E.]

Re: AC Compressor

My experience over the years with A6 compressors rebuilt by a high volume house (like "remanufactured" units from parts stores) is spotty at best. Yes they're guaranteed, but if bad, the expense of discharging, R/R, and recharging the system is on you.

So I learned to either install a new A6 from a major brand, or have an experienced, local tech rebuild MY A6 (as suggested in an earlier post). It's a bit late for you, but it's a crap shoot to re-install an old compressor that hasn't been used in awhile- seals dry out, stuff inside can corrode. In you position, I would rebuild or replace every component in the system, especially the compressor.

[Monte M.]

Re: AC Compressor

Chuck,
I am a little bit late to the party and have a few ideas on what might be going on, but you have a few very knowledgeable people giving you advise at this point and you should follow on the path you are on.

I have helped quite a few of our members get their A/C running on their cars. The real reason I am posting is, you mentioned your compressor may not be the original that came with the car. The 72 compressor is different than most A-6 compressors. For a few years GM had a superheat switch on the back of their compressors.

You can look to see if your current compressor has the superheat switch. If it does, there is a pretty good chance it might be original. But, more importantly, if you do end up having to buy another compressor, make sure it has the superheat switch on it. They typically run a bit more with the switch, but that is just part of the fun of it.

Best of luck,

Monte

[Charles W.]

Re: AC Compressor

Monte,
Thanks for the info. Yes, my compressor has the superheat switch. When I bought the car the compressor was all cleaned up and had the appearance that it was reconditioned. But I was unable to get in touch with the previous owner to confirm.

[Charles W.]

Re: AC Compressor

Mark, I called around here in the Indianapolis area and have not yet found any one that rebuilds the original A6 compressors. I contacted a couple of the corvette parts suppliers and was told that the new A6 compressors they sold did not have the exact appearance as of the original Frigidaire compressor. I have an appointment Monday with a shop that still works on R12 systems. I hope to learn something then. Thanks for the response.

[Mark E.]

Re: AC Compressor

I haven't checked, but maybe there's a service listed in Driveline? Can anyone recommend an A6 rebuild service for Charles?

[Harry S.]

Re: AC Compressor

Mark, I called around here in the Indianapolis area and have not yet found any one that rebuilds the original A6 compressors. I contacted a couple of the corvette parts suppliers and was told that the new A6 compressors they sold did not have the exact appearance as of the original Frigidaire compressor. I have an appointment Monday with a shop that still works on R12 systems. I hope to learn something then. Thanks for the response.

Contact Dom Tallarita, NCRS number is 51287. He does excellent work. Look in the member list to email or PM him. He does a complete tear-down and rebuild as opposed to just replacing the seals.

[Jim T.]

Re: AC Compressor

Charles way back about 1993 I took my 1985 to a shop that serviced my 1985's air conditioning system. All I wanted was a check of the R12 content in the system.
I was surprised watching the check that the serviceman hooked up a R12 machine and removed the R12 and the oil from the system. Seeing the oil he then knew how much was removed into a separate see through container. The old oil was discarded and new oil and my removed R12 plus a little bit new R12 was installed. The air conditioning really worked great after the service.I wish this type of service was still available in my city. Have not found anyone that services R12 locally.
Did find one shop that has a R12 machine still in the shop but not in operation to do any work.
With all the replacement of parts in your 1972's air conditioning system how much R12 type oil did you install?