Eric Kessel

Have you been able to pull any codes out of the CCU with a scantool?

Livefreeandrive

Had the car scanned last month? Do they need to look for something specific? My 02 sensor was toast and a vacuum leak was found?
Rob, I have the bently book which is pretty vague? I should have boght Adrian's book and will at some point.
Steve

Rocket Rob

You will need the factor maintenance manuals to get the wiring schematics. Adrian's book is extremely good but it doesn't have them. I have all three (Bentley, Adrian's and the factory). I will try to look up the circuit tonight to see if I can see how it works.

Livefreeandrive

Thanks Rob!

Eric Kessel

When you do a scan, you read codes from each "subsystem", so the engine will give you oxygen sensor faults, the airbag controller has it's own faults, and the CCU has it's own also. I wouldn't bother with wiring diagrams for this until you get the codes out of the CCU. I'm not sure where you are located, but there must be someone up near you that can read the codes...... If you can't find anyone near you, I've got a board and can read them for you (I'm in MA, near Salem, NH)

Rocket Rob

+1 on pulling the CCU codes. I have a scan tool too, if you need one. I'll still take a look at the schematics tonight, out of curiosity but I seem to remember, the wiring is pretty simple until it enters the CCU.

Rocket Rob

Steve,

I checked the schematic drawings. My memory was right. Its very simple. The power for the rear blower comes from the CCU => relay => rear blower. I would use the Scantool to pull the codes. Hopefully, that will give you a hint. If you run into a dead end and need to try swapping parts with a known good ones, maybe we can meet on a weekend to work together.

Livefreeandrive

Rob, you have the scan tool right?

Rocket Rob

Yes, I have the scantool.

rohanveal

hi Dave,

just been reading up on all this, and i have disconnected my rear blower on my '89 964 but there is still a constant heat trickling into the right side of the car only. is it possible that the RHS 'diverter flap' that is stuck open? if so, how can access this flap and fix/replace it?

rohan

Rocket Rob

Rohan,

You could either have a torn heater hose inside the cabin or a stuck servo.

Servo inspection = http://porsche964.co.uk/technical/servos.htm

Heater overview= https://rennlist.com/forums/964-foru...-problems.html

Torn heater hose = https://rennlist.com/forums/964-foru...t=heater+tubes
https://rennlist.com/forums/964-foru...t=heater+tubes

92silver964

So does that mean if you disable this blower and install the bypass duct (to make more space in the engine bay and remove weight) you are risking the engine since it no longer would have the ability to shed heat at the upper temperature levels?

rohanveal

servos seem ok, but i have found a 10mm hole in a hose duct on drivers side (the hot side) in front of the rear wheel, and will see if i can get a patch on it.

otherwise is there a flap somewhere in the back that i can check to see if it stuck?

-r

Rocket Rob

Rohan,

If you patch that hole, I suspect your problem will go away. Is there a flap in the back of the car? Yes but they tend to be very reliable. The heater hoses and servos are the typical causes of excess heat inside the cabin.

My advice is to fix the hose first. Then report back the results. If necessary, we can explore other possible causes.