Air Conditioning

[Eugene G.]

I had the A/C system evacuated andI sent the compressor, POA valve and drier, to be refurbished for R-12. I am now putting everything back together.
The A/C system in my 70 requires a total of 11oz. I have 6oz in the compressor and 1oz in the receiver/drier. I may be able to get the 1oz in the condensor but I can't see how I can get the last 3oz in the evaporator.
Can I put the last 3oz in the drier or condensor?
Information on 68 and up air conditioning is very scarce on the forum. Never worked on A/C before so any help would be appreciated.
Thank you

[Michael L.]

Re: Air Conditioning

I'm not an AC expert but have been reading about how to service your AC system lately as I prepare for doing some AC work myself. I saw several videos that illustrated an oil injector device to have oil pumped into the system. This may be the most practical way to get the 3 Oz of oil into the system that accounts for the oil that needs to be added. See below.

gohantee R12 AC Oil dye Injector for R134a R22 2oz A/C Air Conditioning Injection Tool Female 1/4" SAE x Male 1/4" SAE (amazon.com)

I would look into this as the best way of adding the oil for the Evaporator.

Maybe others with more AC experience will chime in.

Mike

[Eugene G.]

Re: Air Conditioning

Mike,
Great idea! I thank you for your input.

[William F.]

Re: Air Conditioning

Where did you send POA valve to be refurbished? Please tell me if it works when you turn AC on?

[Eugene G.]

Re: Air Conditioning

William,
I sent it to Old Air in Tampa, FL. I'm still working on the system. The last part I will be installing is the receiver/drier.
I will let you know how successful I was.

[Michael G.]

Re: Air Conditioning

Eugene, did Old Air do your compressor and POA ?

[Eugene G.]

Re: Air Conditioning

Michael,
Old Air did the POA and the drier. Domenic Tallarita in California did the compressor

[Tom L.]

Re: Air Conditioning

Oil in a/c systems continuously circulates. It's not like engines where oil control is important. The 1 oz in the recieiver, 1 in the condenser and 3 in the evap are what would be "expected" during normal operation. What is important is that the compressor has what it needs. During operation oil will naturally flow from the compressor, to the reciever, to the condenser, to the evap and back to the compressor. It will continuously circulate. I think that as long as the compressor has what it needs and the remaining oil (11 oz. as you mentioned) is added to the syestem at some point you'll be good.

In commercial systems I have NEVER added to or been told that oil should be added to specific parts of the system. Typically commercial systems are assembled with all components dry and oil is only in the compressor at start up. The assumption is that there is enough oil in the compressor that will maintain the proper level in the compressor as oil continues to circulate. On the other hand, on larger systems oil levels should be monitored and adjusted as needed. But that really doesn't apply here.

And old Air rebuilt my POA valve, they did a nice very job considering what the process is.

[Eugene G.]

Re: Air Conditioning

Tom,
Domenic makes sure that the compressor is returned with the correct amount of oil in the compressor.
I appreciate youir feedback.
Thank you
.

[Michael L.]

Re: Air Conditioning

As I said I'm not an AC expert (actually, Tom is) but I think what you can't do is add all 11 oz the system needs to the compressor. I think there is a chance doing that could lead to a seizing of the compressor and damaging it. But like Tom said, once the system is running the oil distributes around the entire system. That oil injector I listed above is just a way to add the additional oil that isn't in the compressor that needs to be in the system without the need to pour that oil into each of the other elements.

[Domenic T.]

Re: Air Conditioning

I might disagree about adding total system oil (11oz) to the A6 compressor. The oil that would be in the compressor pan cannot get out as it would have to find it's way past the rings. Also there is not a oil by-pass in the oil system of the A-6.
My guess is that excess oil from the compressor would build up in the first station from the pressure port.
Would take a miracle to get 1 oz in the condencer, 1 oz in the drier, and 3 oz in the evaporator, and leave 6 oz in the compressor.
The A6 oil system is very similar to a gasoline engine . it has a oil pan separate (wet sump) from the pistons and rings. the oil pump picks up the oil from the pan and it go's thru the crankshaft to 3 places, 1 is the rear shaft bearing and thrust washer bearing, 2 is the front shaft and thrust bearings, and 3 is the front seal. The oil that escapes the bearings oils the piston cylinders and thru a small hole under the ring by way of a splash system.
for what it's worth.

Dom

[William F.]

Re: Air Conditioning

Tom,
And the POA refurbished by Old Air works. Was it just cosmetics or did they diassemble and restore to working order?

[Tom L.]

Re: Air Conditioning

William, in terms of the rebuilder, I was talking off the top of my head, I can check though. I did bench test mine (found a you tube video on how to do it) and it simply didn't function at all. From what I remember they seperate the valve at the thin flange, rebuild the guts and weld it back together. Then calibrate it for the refrigerant being used.

"Off the top of my bald" head I think there's a 2 or 3 psi difference between 12 and 134a to maintain the correct evaporator pressure/temperature. Here's the rason:

A POA valve in my world is just an evaporator pressure regulating valve. (Don't even remember what POA stands for or actually means) IF the pressure in the evaporator is costantly at 37 psi (and don'y know that 37 psi is the correct setting, just guessing) the temerature of the evaporator would be a constant 40* insuring that the evaporator would not ice up. That's whay recalibration is important. If you look at a P/T chart and educate yourself on the relationship between temp and pressure you'll think that the difference is minimal. Not an engineer but it apparently makes a difference in practice.

[Joseph S.]

Re: Air Conditioning

I hate to be the bearer of bad feedback on a service provider, but my experiences with Old Air in Tampa were quite different. I sent a STV (I was working on '66 car) to them for reconditioning, two separate times. First time it was returned leaking profusely, the second time it held pressure but did not operate (piston stuck in bore). In addition account poor packaging, the valve arrived with the plastic vacuum port broken off, which continues to be a problem. In my many followup discussions with them (no return calls/not helpful at all) I was told they have no way of testing the valves. They take them apart and reassemble- in my case not very well and hardly a rebuild. Needless to say I was very disappointed with their service- I hope your experiences with a POA are better.

I ended up sourcing a diaphragm and piston on line, with the help of guys on this tech discussion board (thank you Larry Mulder) and by following the rebuild instructions in the GM service manual I was able to successfully rebuild the valve and it now operates and holds pressure.

All that being said I have a working POA (I checked it by piping it into the system and testing) if someone would like to use it to check their system.

Joe

[Tom L.]

Re: Air Conditioning

I just went and checked, I did use Old Air in Tampa. It was in winter of 2014, not sure when you had your experience but perhaps things have changed. As these cars get older it seems to be geting herder and harder to find vendors that can do the work we need.