964 Climate Control Troubleshooting
 

Last month (December - winter in NY), I purchased a 1991 Cab C-4. Unfortunately the Climate Control does not work properly. The symptoms are:
1) Constant heat from driver's side & middle vents. Far right passenger's side vent blows cool air.
2) Round thermostat dial (blue & red dots) does not work.
3) Slide Controls appear not to work.
4) Blower fan 0 to 4 does work properly.
5) Defrost button engages & blasts air through vents not to glass.
6) A/C button turns on (yellow light) but the condenser/compressor appears not to engage -- no change in RPM's, etc.

I have Adrian Streather's 964 book & it appears that the two mixing chamber Servo valves under the front hood may be bad. Any other ideas?

Thanks. This is my 1st post!

Pete

Hey Pete, congratulations on a beauty purchase. I cant offer any technical help personally but take a look at (www.porsche964.co.uk)
follow technical link, to electrics, and at the bottom is an excellent article on the heating and servo repair. Loads of photos! I doesnt look to bad to fix. similar problems were described. I hope it helps.
Darren
By the way just purchased'91c2 coupe in December in Canada.

Do anyone know where to find above article about servo repair? It has been referred in many posts but looks like www site is no more working.
I may have heat servo trouble and would be nice to see how one has repaired them.

The most common fault in the servos are weared-out potentiometer tracks and burnt whiskers. This is not possible to repair, you'll have to get a spare. I have seen very few, if any, other faults in these units.
I've got a newly updated Porsche HVAC page here, I doubt you'll need any more info than that. ;-)

Here's a cached version of the 964 page mentioned above.

Cheers,
Tore