My a/c never worked since I bought the car last October. I would like to fix it over the winter. Before I start dumping $$$$$ into it, I'd like to learn from other's mistakes. Your story and/or advise is highly appreciated.
Thanks
Stan

 

There is nothing particularly unusual about the Porsche AC system. "Not working" is not a good start to get questions answered. You need to describe the symptoms. Set the controls to max cool, and make the following observations:

1) Is the compressor turning?
2) Are the inside fans blowing air?
3) Is air coming from the selected vents?
4) Is the blown air colder or hotter than the outside or cabin air?

Most "not working" systems have a freon leak. If enough leaks out, the compressor will not turn because there is a low pressure switch designed to protect the compressor. You can jumper the switch momentarily to verify the compressor is OK. If the compressor turns, the next step is to check the system pressures to see if it needs gas. If it does, the leak needs to be found and fixed first. If the freon charge is OK, and the compressor will not turn, there is a fuse blown, and bad switch, bad control module, or other electrical problem.

How much did you beat the seller down for the inop AC?

Good luck

 

When I bought mine, the compressor would cycle, but no cold air would blow. Added 24oz of R12 and now it blows very cold.

FYI, previous owner had condenser replaced 3 years ago. Part cost $476.49.

 

The pathetic part is that when I bought the car the ouside temp. was below 40, so the air seemed to be blowing cold and the seller said that the a/c is working good. When I went back to him this June, he said "Sorry, but it worked when I had it."
I will start with checking for leaks first.
By the way, someone mentioned to me that my car has the "old" style frion system and that the fitting where you fil the gas needs to be updated first. Does any of this make sense?

 

The "old" style is R12, more modern systems use R134, the Porsche system can be retrofitted to R134 with the changing of some fittings, a new receiver-dryer, the removal of old lubricating oil and refilling with the new stuff. I had this done last summer since my a/c was dead as well, figured I'd do the responsible thing and refill with the eco-friendly new stuff. Rumour has it the R12 is maybe cooler, but it works pretty well now, except on those 35 degree humid days, when it's just adequate. A black on black car doesn't help... I know less than zero about fixing a/c systems so I just took it to Downtown Porsche and let them deal with it. (no affil, blah, blah)

 

Hi Stan,

I re-charged my RSA back in early July. I tested the system by removing the cap on the large tube side(low-pressure return) of the compressor. Mine had only one fitting on the compressor, making it pretty much a no-brainer... A quick press of the shrader valve stem that was hidden under the cap proved that I had pressure in the system - some R 12 escaped as a gas.

Consequently, I knew the system had some refrigerant in it and that there were no gross leaks. I put some R-12 based sealant/lubricant into the system (approx 1 oz.) from a can of that material I have around. I then put in two 14 oz cans of refrigerant 12. The compressor low-pressure switch was "made" (closed) as I added the first can, and the compressor clutch engaged. Bingo.. working A/C. I hope your fix is this easy.

Some systems will have a micro-leak (around a seal or at a joint) that will cause a charge of refrigerant to be lost over the course of 3 or 4 years. Very often for me, a lack of AC functionality has been just a lack of Refrigerant. Cycling your AC often and using it in the winter as a defrost function tnds to keep all of the seals "happy" and working at their best.

Doug B

 

Thanks Doug!
I am sure I am not the oly one here who would like to see some more details on how to do this. If not too much trouble, could you even point out where to look for "the shrader valve stem that was hidden under the cap", as well as the brand name of the sealant and any other usefull info you can think of.
Thanks a lot

 

Hi Stan,

The Shrader valve is a technical word to describe what is essentially a tire valve. Just press the litle post/plunger in the center of the valve as you would to bleed excess air out of a tire. You should get a hiss of gas. However, if the system is completely void, you run the risk of simply "dumping" the r-12 into the atmosphere if there is a leak in the system. That is why I check the valve under the black cap first for that telltale "hiss".

At the present time R 12 is not widely available any longer at retail. I still have a couple of cans that I bought before it went off the market. I have the hose and can connector set-up specific to R 12 that has been "kicking around" my garage for years. According to the current US laws, a person may use their existing stock of R 12 as I understand it. The sealant that I described and used is at least 10 years old and is likely no longer availalble through that manufacturer.

See if you can find some R 12. Check out some garage sales/flea markets Etc. and the stuff may turn up. When "armed" with a couple of cans of R 12, you can re-charge your system with the material it was designed to use, and get the highest efficency of the system. A friend recently told me that a 12 or 16 oz can was selling at approx $75 USD at the dealers and A/C service establishments- These establishments must buy the marterial through current channels/sources -- pay the high tax...consequently the higher prices....

However there is an interesting split in the automotive refrigerant business. The USA market has been using R 134 A for a number of years it is the most popular refrigerant. 134A is not flammable at all. However HCFC type of refrigerant gas has a much broader market presence in Europe and Canada but it is marketed and sold in the USA as well. HCFC's are flammable , but pose a very small risk vs reward in my opinion. Remember, you have a fuel tank just in front of your feet....as compared to a gas that is theoretically trapped in a system.

However from what I understand, the HCFC appears to work more efficently than 134a- especially in cars that were originally designed to use R 12. I'm not sure what changes should be made if you make the conversion from R 12 to HCFC.

It might be worthwhile to check on the availability of the HCFC refrigerants by contactig a vendor. A call to a vendor of HCFC refrigherants might give you some good information. Speaking with their technical department and asking about the compatibility of the HCFC to the R 12 Porsche A/C system of our 964's would seem to be a good idea When my R 12 "stash" runs out, that is what I plan to do. I will not convert to 134 A type refrigerant for a system that was designed to be running R 12 until I thoroughly evaluate the HCFC option...

Perhaps others have been running the HCFC type refrigerant already with good sucess??

Doug B

 

Many 964 owners have had good success with R-134a conversions. The system was designed with R-134a in mind, as Porsche knew it was right around the corner. In fact, the differences between the R-134a 964 system (1993, IIRC) and R-12 systems are very minor. I don't remember ever reading of a 964 owner who was dissatisfied with an R-134a conversion.