[coolbear1]

I converted my 88 e30 cabro to 134A.
You should first find your leak.
I assume there must be some R-12 left or the compressor would not come on at all. Unless you are jumping the pressure control out.

If you can get ahold of an electronic leak detector, an R-12 leak is easyer to detect than if you replace it with R-134A, because of the ozone depleting clorine in it that you have heard so much about. This is a good reason to for the leak first.


There are several ways to approach a retofit to 134a.

Sometimes you can take shortcuts and get away with it. I would not. most of the time it will cost you more in the end.

I always recomend removing the compressor and draining the oil.
Some people don't, but the oil in it will not mix with 134a. Kindof like oil and water.
The problem with this is in an air conditioner, some of the oil circulates around the system with the refrigerant. If it will not mix, it can log up in the system somewhere, (usually the evaporator). It woun't return to the compressor in sufficient amounts and it will cause the evaporator to loose efficency.

The O rings in question, are in the refigerant line connections, Evaporator inlet, expansion valve connections and reciver drier connections.
They need to be replaced because they are not compatable with the refigerant and the new style oil.
The 134A will attack them and cause them to leak. So take the lines loose and flush them good with system flush. It is available in pressurised cans, It is basically synthetic oil and 134A, and wont harm anything if you don't get 100% of it out.

There is one also in the compressor shaft seal, But it is not feasible to change it in most cases.
It usually will last, at least as long as you might expect the compressor to last. Sometimes years.
But I have seen them go the day after a retrofit. Never know.
If it does start leaking you will have to get a compressor.

Flush the condenser and the evaporator coil also.

Also, 134A works at slightly different pressures, temperatures and velocities than R-12, so the expansion valve that meters the refigerant into the evaporator should be changed to a 134A valve.
.
You need to also install a new recever drier.
The POE and POL synthetic oils are very hygroscopic, (absorb water)and do not react will at all with moisture. Water will break down the compounds in the oil over time and you wil end up with something other than oil.

If you do these things,and pull a good vacuum, avoid air, and moisture contamination, you should end up with a system that will perform well for years, assuming your existing components are healthy.

Good luck.