About 6 weeks ago I met up with another Rennlister and we topped off the R134 freon and used a sniffer to find any leaks. After an hour of searching, the sniffer couldn't find the faintest hint of a freon leak.

The system has worked great until yesterday. I drive the majority of the time with the top down and rarely need the A/C. But I hit the A/C button at a traffic light just to check to see if it was still working. The compressor clicked on but the air was warm and never got cold.

I guess this will be a winter project to find the leak and replace the part.

 

Has anyone successfully used the freon with dye in it to find a leak?

 

The 964 is known for evaporator leaks. The unit's under the dash so you might not be able to detect the leak without pulling things apart. I have a slow leak which requires a yearly refill.

 

I'm going to check all of the other pieces first for signs of oil. If everything is clean, I'll dig into the evaporator this winter. I've had the car out of commission too long already this year doing the reseal.

Thanks!

 

FWIW: I have an extremely slow leak at the Schrader (sp?) valve where new R134 is introduced into the system. My mechanic says that a small leak there is common for all such type valves. Said to come back when it leaked enough to need refilling more than once a year. I believe the necessary replacement part is very expensive. It's been more than a year since the last top-up and a/c still blows cold.

 

My leak is at the expansion valve

 

We went all over the compressor and not a hint of freon. The system was fully 2 months ago and blowing ice cold. Now, warm air. It's a shame Porsche couldn't put any build quality into their A/C systems.

That is a pretty easy fix - minimal tear down needed.
BTW - goregous 993

 

Thanks Big Mike. It's getting replaced as we speak.

 

I find my leak in the A/C system in the past 3 years. In this period many major parts were replaced. The condenser, evaporator, expansion valve, 3 way pressure switch, dryers, compressor, high and low pressure refrigerant hoses... The weakest parts are the O-rings in the entire A/C system and the expansion valve. I used two expansion valve in 3 years ownership. The 1st one is OEM, only last 1 year. The 2nd one is Porsche brand so far no problem unit 9 month now. When leak appear at expansion valve, you can see bubbles coming out from the circular gold color cover. The hidden O-ring also need to pay attention to, like the O-ring at the high and low pressure refrigerant hose which across the rear left wheel well. This is my last leak take place. If you are using R12, and the service port still R12 version, R12 service port valves are easy to leak even when new. It is better using 134A service port even still using R12.

Rear left wheel well lining removed, you can see high and low pressure A/C hose


Sponge like fitting cover the joint will hidden the leak


Video show expansion valve leak. You can see bubbles even you didn't switch on the engine

 

I made a list this morning of all of the o-rings that I can find in PET. There are about 15 of them total.

My question is, if I'm running R134, do I need to find R134 o-rings instead of the factory R12 o-rings?

 

I heard R134 O-rings are stronger (thicker) to withstand higher pressure of R134. I am using R12, but the o-rings are R134.

 

This kit looks to have all of the sizes needed (or really close).


- Kit Includes:
- 7/32" x 1/6" (5.29 x 1.78 mm) (25 pcs)
- 1_4" x 1/16" (6.07 x 1.78 mm) (20 pcs)
- 6.8 x 1.9 mm (20 pcs)_
- 5/16" x 1/16" (7.65 x 1.78 mm) (20 pcs)
- 7.8 x 1.9 mm (20 pcs)
- 8 x 2 mm (20 pcs)_
- 8.8 x 1.9 mm (20 pcs)
- 7/16" x 1/16" (10.82 x 1.78 mm) (15 pcs)
- 7/16" x 3/32" (10.77 x 2.62 mm (15 pcs)
- 11 x 2 mm (15 pcs)_
- 12 x 2 mm (15 pcs)_
- 13.9 x 1.8 mm (10 pcs)_
- 9/16" x 3/32" (13.95 x 2.62 mm) (10 pcs)
- 14 x 2 mm (10 pcs)_
- 15 x 2 (10 pcs)
- _17 x 2 (10 pcs)_
- 11/16" x 1/16" (17.17 x 1.78 mm) (10 pcs)
- 11/16" x 1/8" (17.04 x 3.53 mm) (10 pcs)

 

Not sure Griffiths post can be helped.
https://rennlist.com/forums/964-foru...ng-system.html

searched:
#6 is 6/16" (3/8"),
#8 is 8/16" (1/2"),
#10 is 10/16" (5/8") and
#12 is 12/16" (3/4").*