bbain

I had the dreaded “hot air only” syndrome coming out of my vents. I searched this forum and once again found excellent information. Thanks to all. Here’s some additional information I learned while fixing my problem.

Vacuum Check Valve
In checking the usual suspects (clips, vacuum hoses, HCV) I found that the vacuum check valve had broken. While researching a replacement I found an identical, and less expensive, vacuum check valve with a VW/Audi part number. Here’s the details of the two parts:

- Porsche vacuum check valve (928 537 361 02).....$20.00
- VW/Audi vacuum check valve (433 862 117)..........$2.25

Climate Control Unit
Unfortunately, my hot air problem still existed. I decided to replace the climate control unit and found a used one out of a 95 968 for a very good price. The replacement unit arrived with a cracked trim piece as well as broken mounting tabs on the clear plate. I suspect this happened when the dismantler removed it. Since my trim piece is perfect that was no big deal, but the mounting tabs were a problem. Thinking I could easily swap the broken clear mounting plate with my perfect mounting plate was just that... wishful thinking. It's a bit involved. I found an awesome post detailing how to swap out the clear mounting plate here (http://forums.pelicanparts.com/porsc...trol-head.html). Thanks to kdjones2000 for the write-up (I gave a thank you on the other forum as well).

After swapping out the mounting plate, as described in the above link, I installed the replacement climate control unit and no more hot air.

Climate Control Unit Removal
For me, the hardest part of removing the climate control unit was removing the trim piece while not breaking it. As noted in other posts, the trim piece clips on over the control unit clear mounting plate. After removing the air directional slider ***** (the fan speed and temperature ***** do not need to come off), I used a jewelers screwdriver to gently pry behind each side of the trim piece. Once the trim piece had started to loosen, I used a small bladed tool with a right angle (it’s actually made to remove chips from circuit boards) to gently pry on the top of the trim piece and it came off.

With the trim piece off, I pulled on the center of the clear plate where the graduation marks are and the unit came right out.

Hope this helps.

dougs968

Thanks for posting that. The more good info, the better. Really like the crossover part numbers. It's good to have an alternate source for parts.

sm

Thanks for the post. Where's the check valve located?

bbain

The check valve is located on the right side of the engine near the battery. It is blue. There is also a vacuum tee nearby. It is represented in illustration 813-25 in the PET.

calguy

Awesome info! Thank you for the write up! I've been meaning to replace the clear bracket since a new control unit costs a bundle!!

Calguy
'80 924 N/A
'92 968 Cabriolet

John Etnier

I have been away from this forum for a while. I have had the following condition for a few years now:

1. Temperature control is biased quite high: 12:00 ("normal") would be much too hot in all cases.
2. Heat comes on unbearably strong in extreme cold, unless recirc is engaged.

Are these conditions known to others here? If you think I should, I'll start a new thread for this.

bbain

Sounds like it could be one of the sensors or possibly the climate control unit... and these are just guesses. I don't know of any way to check the climate control unit other than swapping out for a known working unit.

Since the fix to your problem could be something other than the climate control unit, starting another thread might better serve you. You could always reference this thread if needed.

Good luck!