Vandit

Looking through that P-car DIY write-up, are all the steps in there beyond the evaporator replacement advisable best practices? Running that system flush? Dismantling the compressor and adding oil? Please advise.

CraigC

I had the same issue with my ac a couple years ago and assumed it was the evaporator. I didnt want to tackle removing the gas tank so i took it to Ruf in Dallas. Im glad i did because it was the accumulator if I had done the work to pull the gas tank and replace the evaporator it would have still not worked because the accumulator was plugged up and it would dump the 134a I put in because there is a relief valve on it.
They did a great job at Ruf and Im sure I saved some money and frustration by having it diagnosed right to begin with. Craig

Vandit

Where is that part located?

EDIT: I believe you're referring to the drier?

I'll make removing the front left fender liner one of the first things I do, as if the refrigerant is indeed being bleed off at the drier, then I assume there should be evidence of that on the drier?

Earlydays

Just got my AC fixed - new evaporator (OEM), dryer, expansion valve, O-rings and converted to R134a....cools great!
The dryer should always be changed when the evaporator is changed.

Vandit

Did you DIY or have a local shop handle it?

Earlydays

Local shop....the experience of the shop, plus the warranty justified the labor expense in my mind.
Also replaced a leaking front oil cooler at the same time.

ducnine

I just did the r134 conversion this week after no AC for 6 years. Wow its feels great now. Was thinking about doing it myself but just had my local do it. It was worth it. They checked for leaks, replaced some gaskets, new reciever/dryer and r134 futtings on the comoressor.
But now my 25amp blower fuse is blowing out. Gotta figure that out.

jimq

I tried a search for the quantities of oil and R134 used in a conversion but cant find it. I know it was posted not so long ago. Anybody have the numbers handy? I want to change the drier and O rings and then take it to be recharged after 4 years. Any thoughts on what is a reasonable priced yet good quality dryer to use as a replacement?

Vandit

I believe it's 840g of r134a per the Porsche manual, so basically 2.5 of small r134a cans. I think the general rule of thumb is 80% of the R12 charge for retro cars.

RicardoD

In Adrian's book:

R12 refrigerant (1989-1992) 930g (2.05lb) Densoil 100 20+/- cm^3 (3.4oz)
R134 refrigerant (1993-1994) 840g (1.85lb) ND8 140 20 +/- cm^3 (4.7oz)

m_a_saunders

During the last winter I had the evaporator replaced with a Kuehl unit as well as all pipes, o-rings and the compressor,etc... Now after 10 years without a properly functioning AC it works thanks to Fach Auto Tech in Sattel, Switzerland! But don't expect it to work like a modern 3 or 5-series BMW with the max air conditioning switch... Honestly, I still like opening the windows and sunroof and giving the car a blast around those alpine roads on a sunny day... Cheers, Mark

jimq

Thanks guys. Any suggestions on a dryer? Rockauto has a couple for a good price they say fits the 964.

Vandit

That's a good question and I can find anything online that gives detail. I don't know if all aC driers perform equally. Is it like an oil filter, where certain brands and internal construction differences yield superior performance?

Just checked, Rockauto has driers for like $15 while other Porsche-specific sources sell them for $60-70. That's such a big margin.

The one I just took off my car was "made in China" and probably installed by whoever did the initial R134a retrofit. I still have not ordered a replacement.

jimq

Another question. Is it a good idea to change the expansion valve while the system is open and is it even in a place that I can get to without taking the whole firewall area apart?

RW964

Hey Vandit while you are in there as Tbennet was talking about lube the fan motors I just changed the left side out also pulled the right side out as 24 years old I used a plastic syringe with a curved tip on it about 3 times a day I would drip a few drops of 30 wt oil took about 4 days and I was done really easy. I figured it lasted all these years and the fans were ready for oil. Picked up a used fan at D C Auto was $360.00. So doing this you will save at least that much. $1050.00 new. Use the hacksaw blade method I had to at the end pull on the blower shaft to get the fans to come out after getting them loose. A couple drops will go a long way ...