A/C Recharge
 

I have a 1991 964 and every 2 years or so the R12 freon goes away.

It's way to expensive to recharge anymore and there hasn't been a leak detected in the past. My shop says that to go 134 I should change the drier. 134 seems less effective and corrosive. I was told by a friend about Freeze 12 and Autofrost as alternatives which he has used in his vintage muscle cars without a problem. And it seems to be cheap!! Thought or experiences?? Thx... Mark

Our cars are known to have 'porous' hoses and untraceable leaks.
I have used dye and other methods and never locacted my leaks.........
So, i have grown resigned to topping off the system every 2 years or so.

That being said, R-12 is without a doubt the best freon.
Even considering the cost, i suggest refilling with R-12.

R-134 runs higher pressures and is not as effective cooling.
You can convert to R-134 without changing any oil or the dryer.
Your tech just needs to be aware that the system will require more qty R-134 than the conversion charts show and the pressures will run correspondingly higher than a R-12 system.

WHATEVER YOU DO, DO NOT USE FREEZE 12, AUTOFROST OR ANY OF THE OTHER SO-CALLED FREON REPLACEMENTS.

These products contain propane, methane, esthers, alcohol, and other contaminants which are ineffective, dangerous, corrosive, and will eventually kill the environment, your system and possibly your tech.

The hoses in the 964 a/c system were engineered to use both R-12 and R-134a. They are not the old tech hoses that are designed to leak but are barrier hoses that operate under the higher pressures required to run R-134a.
If your car was delivered from the factory with R-12, there are 12 o-rings that will need to be changed out, as well as the receiver/drier and the fittings on the compressor.
R-134a has the ability to remove more thermal energy from the air than R-12. Usually the conversion process gets botched and improper operation is the result.
My opinion is that if you are going to spend the money to convert, go all the way. A receiver/dryer costs $30. Why wouldn't you replace it? It takes 10 minutes to drain the old oil out of the compressor. Why not do that?
Find a shop that has a reputation for working on Porsche a/c and work with them. If you can't find that, buy the "Without Guesswork" book, copy the R-134a High side pressure vs. ambient temperature graph and hand it to a good shop. If they are any good at all that's enough info to get a quality job done.

Can anyone recommend any Porsche A/C shop around Pasadena California? Thanks.

134 Thoughts
 

Thanks for the R134 thoughts. That seems to be the route I will go. I have a very good shop here in So. Cal but they sub-out their a/c work. I was quoted $500.00 to change the drier, add the compressor fittings and re-charge w/134. It seemed like it was a bit high and there was no mention of any O rings to be changed. I would also like any thoughts on a So. Cal shop that does their own a/c work.

I got quoted $1500 :eek: by the local Porsche dealer. I re-charged with R-12 as I found some cans I had bought in 1980.
The next charge will be with R-134a.