I've read other posts regarding replacement of the A/C switch and /or the recirc. switch. but I'm not sure if I've got a bad switch or a bad control unit. A month ago I noticed the A/C blowing less than ice-cold air. I decided to take it to the local dealer to have the system checked out- as it is nearly 12 years old and I didn't want to run it if it was not properly charged. Well, after another very discouraging encounter with the service department, I was told that the recirculating switch was bad and was replaced. Within days, the A/C stopped working. The compressor does not engage when the switch is depressed (the little light on the switch is on). The blower works fine. I would normally assume it's the switch, but having just replaced the recirc. switch I'm wondering if this is indicative of a greater failure. What does the "Control unit" actually do? Should I try the switch? I'm not sure I'll be able to return it once I've installed it.
Finally, My '91 C2 is at the age when little things begin to break, such as the little arm that lowers the wind deflector as the sunroof is closing. I love my car and take excellent care of it, but as plastic gets old it gets brittle, so these things will happen. My problem is that I've relied on the local dealer for hard parts such as this,and I would be very happy to never have to buy from them again. Is there another source for such specific Porsche parts?
Thanks in advance for all your input and advice. This forum is fantastic!

 

Hi,
There have been a number of posts about air con recently, and one thing they all mention is that the compressor will only engage if you have adequate gas in the system. It could be that the head unit is faulty - but it's more likely that your air con has a leak and the compressor is not engaging because the gas has leaked out.

Dave
90 C4

 

Dear Sailor,
I have to say that I do not quite understand the mentality of some of the mechanics used for 964 repairs. Either that or the posts are not complete in their descriptions of what the mechanics did.
The recirc actually plays no direct role in the aircon systemoperation. Works whether the button is pressed or not.
There are many things that "MUST" be carried out before speding a huge amount of money on control unit repairs.
1/. Check all the fuses on the engine carrier plate. The compressor will not engage if the fuse which powers the cluch is kaput.
2/. When you depress the aircon switch you say the little light or led in the switch comes on. This tells me that you have an electrical circuit. I still recommend a fuse check this is why it is first.
3/. Check the wire (just one wire) which feeds the clutch to see if it is damaged.
4/. Service airconditioning system properly. Pressure check etc. Whether the compressor engages or not, the system must still be pressurised.
From your post I feel you have ahole in the system somewhere. You will never know until you have a pressure test carried out,
Ciao,
Adrian
911C4

PS: You should feel very lucky. I have never ridden in any Porsche of any model which blows ice cold air from the standard aircon system. Unless of course it is -20 degrees outside.

 

Dear Dave and Adrian,
Thanks for the info. I too am not sure why these 964 mechanics do what they do, hence my disgust with the dealer's service dept. They are set up with a service manager whose job it is to keep customers away from the mechanics. He simply relays info. back and forth betw. the customer and the mechanic with much lost in the translation. I've gone to great lengths to describe a sympton in such detail that a mechanic could easily narrow down the cause, only to later see on the work order something like "check engine"! Then, when I go to get my car, I find they have done unnecessary work ($$$)and not solved the problem I requested in the first place. It's happened this way nearly every time I've brought my car in for service. I'm not totally ignorant when it comes to things mechanical, I've rebuilt a couple of motorcycles and small machinery, but since I've owned this car I'v insisted on paying "experts" to work on it, to avoid costly mistakes. When I picked up my car after the last visit to fix the A/C, the service manager informed me that they had to replace recirculating switch AND the "Idle Control Switch" because the car would not idle properly. After some discussion he told me that they really didn't have any mechanics who were knowledgable on these "old" cars. That was it! I really don't have the time or the energy to wage a legal battle with them over unnecessary repairs, but it has really begun to sour my 964 experience. However, I'll quit complaining and begin with your check list to see if I can determine the problem using your helpful advice.
Now, one dumb question.... What's the engine carrier plate? I've not heard that term before, is it not the fuse panel in the luggage compartment? (I've already checked each of these fuses)
Again, many thanks.

 

Good luck on getting the air conditioning fixed. I was under the impression that the resistor in the left front wheel well had probably stopped working (battery overflow damaging it, etc.). Bought a new one and took it to the dealership in Salt Lake City. This guys been working on Porsches for many years. I was allowed to go talk to him, explain why i thought the problem was the resistor, etc. He recharged the R12 and I had coolish air going home. It's not like the R12 cooling in my 85 Golf, which really is great. Our Grand Cherokee has the R134 and in the high heat we've had here recently, it's had a hard time cooling at temps over 95, especially in town. Not so bad when on the freeway and the compressor is going faster. Good luck. <img src="graemlins/xyxwave.gif" border="0" alt="[bigbye]" />