McIntosh

Anyone have any experience returning the original AC system to service? I have an original AC car and all parts are there. AC doesn't work but it does hold a good vacuum. Whats the likelihood of replacing the compressor, POA valve, and drier and having a working system? Is there any chance of the hoses and evaporator holding up for more years?

Anyone want to weigh in on refrigerant? I have a good friend who's a AC tech with a bunch of R12 I can have for free. Any reason I shouldn't use it? Or should?

Hammerdrop

Why doesn't you friend, the AC tech, just put in a charge of R12 and try it? I assume he checked for a tight system using a micron gauge. At the very least, I would probably just change the receiver/dryer, and look for any signs of oil indicating leaks. Also check the compressor and make sure it turns before charging.

chip-powell

Ditto above. And if you have a friend that is willing to give you R-12, take him up on it. That stuff (if you can find it) is going for over $200 a bottle around here in Maryland. That's why I converted over to 134 a few years ago.

chip-powell

Does the a/c blow at all, even if it's not cold?

Fun71

When you say “AC doesn’t work” what exactly do you mean? There’s a lot of room for interpretation there.

dc2x4drvr

I wouldn’t add R-12, before replacing the old A6 compressor, drier,and O rings, send the POA valve out for a service ( the valve isn’t available anymore).
Good Luck!

chip-powell

We used to have someone on this site that refurbished POA's to convert them to 134. He did mine 5-6 years ago. I'll look through my old invoices and see if I can find his name if you are interested.

McIntosh

Yes, the AC did blow. Just not cold. We did put some refrigerant in a few years ago and the compressor didn't seem to make any pressure. The clutch did engage, but it didn't make pressure. Thats why I assume I need to change the compressor and maybe the POA. I'm thinking maybe I should flush out the lines, evaporator, and condenser with something. I assume theres a product for this purpose.Maybe theres a suggestion for that? Replace the compressor, POA, and drier' and try again.

chip-powell

If you're converting to 134, I would say replace the POA, evap and the dryer at least. If not, usually the leaks start at the connections on the hoses. Have your buddy run a pressure test on the system. He should be able to tell you where the leak (if there is one) is coming from.

Fun71

There were 2 recent posts about compressor rebuilders that can retain the factory decals and overall look, assuming you want to keep an original compressor.

If you car is like mine with a reman compressor, just get another from a reputable rebuilder, and of course use R-12 since it’s available to you for free. Your system will cool much better with it.

bw1339

I would:
- Replace all o-rings
- Flush system
- Reseal compressor (likely all it needs)
- Test POA valve with compressed air
- Add new oil, vacuum test and recharge system with R12 or favorite R12 replacement gas

drop top olds

My system was charged with R12 after I replaced the compressor years ago. I cooled better than any R134 system on a modern car. The only advantage a modern HVAC system had over my system was in the blower speed. I could set my system on cold a low fan speed and AC and it would run you out of the car after 5-7 minutes. Temp at the vent was low 40s. Sadly my rubber hose sprung a leak so I will have to go through the system again. I would use R12 before R134. R134 refrigerant also runs at higher pressures and temperatures on the high side.
Replace compressor and o rings
Replace rubber hoses
Check POA valve for operation
add correct oil for r12
New drier
Flush system
Pressure test then fill.
It should last a long time.

classicmuscle442

You say you put in some refrigerant, how much? System will not build high side pressure until you get close to a full charge. When you added refrigerant did the low side pull into a vacuum? Where was the leak in the system? Drier would need replacement but would pressurize system with nitrogen to leak check.

cjsdad

If the system has not been opened for any length of time it will not have dirt or debris in it so no need to flush unless the compressor has exploded and released shrapnel into the lines. That would create a whole new bag of cats to deal with. If you are able to pull a vacuum on the system, any leaks you may have will be very minor. Do a VERY close inspection of the hoses to make sure they don't have any surface cracking or oil stains from porosity. Make sure they are not dry and hard, or soft and soggy. If the hoses are in good shape you should be ok to re-seal and move forward. As long as the system has not been open to the elements you shouldn't need to replace anything but the compressor. Order a replacement from a reputable company or send yours out to the same reputable company for rebuild. Keep the hose ends covered to keep debris out of them, replace the o-rings, and reinstall the compressor. Even though you have a large supply of R-12 there is no need to waste it. My industrial HVAC techs use nitrogen to fill systems and test for leaks after repairs and then purge, vacuum, and refill with refrigerant if there are no leaks. You might want to try that to reduce the lost value of refrigerant if there are leaks. Rubber o-rings can and will last for decades but silicone will last even longer so use the silicone if you can get them.

McIntosh

I really appreciate all the advice. I think I will buy a rebuilt compressor, drier, and POA upgrade in the spring and give it a try. I guess I was thinking about flushing because I don't know if it's already been swapped to another refrigerant some time in its past. Does the oil travel around the entire system or does it stay in the compressor? The system has been and still is closed up. Probably still under some pressure.

bw1339

The reason I suggested flushing was that even if the system was sealed and in good condition, that oil is decades old. Once opened, there is no harm in blowing as much of the old oil out as possible.

Fun71

To answer your question, yes the oil gets distributed throughout the system during operation.

matt69olds

Keep in mind, the A6 compressor front seal is designed to leak just a little refrigerant. It was designed that way to keep the seal lubricated. Just look at the underside of the hood, you will see a line where the pulley has flung oil on the insulation.

You need to keep in mind the the time the A6 compressor was designed and in use. Nobody cared of the compressor had the capacity to cook a small house, or that it was heavy, took a lot of power to run, and wasn’t “environmentally friendly” to the ozone layer. It was durable, and got the job done.

droldsmorland

Free R12 is a no-brainer. Use it if you want to but....
Call Classis Auto Air or Vintage Auto Air to seek professional advice.
Either vendor can rebuild everything including the hoses POA dryer etc using the original connectors.

I wouldn't trust old hoses nor a parts house compressor. Yours turns freely it's probably OK with a simple oil change. For insurance/assurance have it checked out professionally.

With 134a you need different oil (PAG) and PAG compatible O-rings. R12 uses mineral oil. Do not mix! Ester oil is compatible with both refrigerants.
So yes good idea to blow out the old oil.
Replace the parts you think need replacing reassemble and pull a vacuum to see if it holds for 24hrs then fill with the correct volume per the charts. Run/test verify High/Low PSI.

Inspect the condition of the ductwork. Clean the heater core, evap & cond coils. Make sure evap drain is present & unrestricted.
Pull the blower motor clean and oil the shaft. Clean regrease the dash controls. Look at the vacuum lines. Make sure the blend door seal is good and properly adjusted.
Check the recirc diaphragm in the passenger's footwell.
Verify the heater diverter valve is working on the intake to shut off the hot coolant to the heater core.

No need to upgrade to the new POA if you don't want to. The OEM POA orifice can be adjusted to work with 134a. The two vendors above can make that adjustment on the bench. The advantage of the POA upgrade is that it will allow the A6 to cycle like a modern compressor. This prevents icing. Maintaining the correct charge goes a long way to prevent abnormal icing. The upgrade won't look stock.

Regardless the filter and dryer should be serviced at a minimum.
Why chance a hose blowing. Have them rebuilt, more so if you are converting to 134a.
Google this as I thought there's another option that's even better than 134a?
I'll be doing mine soon so I'll be re-educating myself on that.

The attachment is from quite a while ago off of one of the many Vette sites I visit.
The pricing I'm sure has doubled but the other data is still relevant.