964 heater blower burst

Tall02 · 10-23-2005, 04:25 AM

I have a 1992 Porsche C2 964 that has a heater/defrost blower problem. The problem is this: When the key is turned on, the blower goes to max output for a couple of seconds (no matter which blower position is selected on the rotary switch)and then stops. I then have no control over the blower at all and it does not blow at all.

Burst of blower output, followed by no output and no control.

Has anyone had a similar problem and, if so, what was the cure?

The problem is that I am having a hard time trouble shooting this without a wiring diagram. Does anyone have a diagram for a 1992 964, particularly for the heater/defroster blower circuit? I would greatly appreciate it if someone could send me one or give me a good source.

Thanks
Tall02

Britwrench · 10-23-2005, 08:01 AM

Needs diagnosis on the Porsche PST2 or Bosch KTS300 "hammer". The 92 has a AC/heater system that can be "driven" by the tester. Using wiring diagrams won't get you anywhere unless you can find out what part(s) are faulty.

colo964 · 10-23-2005, 09:40 PM

Check the blower fuse in the engine compartment. If it's burned out, the ccu acts whacky.

Tall02 · 11-02-2005, 05:20 PM

I found the problem.

The rear motor in the engine compartment was burned up. Replaced and it works fine now. I guess the burst of air when the Porsche was started was from the two cabin climate control fans. Once they did not receive the rear engine blower air pressure they turned off. Good to know that when the dash air stops check the main rear blower.

Thanks for everyones help