pyramidimaging

The climate control unit, CCU, in my 1991 964 suddenly stopped working. Nothing works not even the little light when the AC button is pressed. Some months ago I unplugged the little fan in the back of the CCU because it was always running and draining my battery. But, the CCU has been running fine since then. I am now trying to sell the car and of course that is when the car paid me back by shutting off the CCU.

I tested the front and rear fuses and cleaned their contacts. They are ok. Not blown. I measured correct 12 volt supply voltages at the rear of the CCU with the connectors removed. They all show 12 volts.

I've read Tore Bergville's very helpful advice at http://www.bergvillfx.com. He also previously posted on another thread:

I'd start with checking two fuses (28 and 17), then check the power supply leads to the CCU.
Pull the unit, and use a voltmeter. Connect voltmeter GND to pin K1 (brown wire)
Voltmeter plus lead to pin K2, (should be +12V permanent)
G29, (ignition switched +12V)
G35, (ignition switched +12V)

Th fuses are good and the voltages are at these pins; however. the CCU seems to have no power at all. Can someone repost the correct pins to test and any other troubleshooting advice on the CCU just to get it to power on?

STUARTQ

Good luck with this, it's the only bug I've had with mine apart from an oil leak which was simple to deal with.
Mine will have to dealt with at some point, but it's one of those jobs I keep putting off.

klr10

Try looking through this, seems to have a lot of good info.

https://rennlist.com/forums/964-foru...t-failure.html

pyramidimaging

I finally had the time to get back to my '91 964 and was able to fix my CCU problem stated above.

I learned a long time ago that the weakest link to any electronic system was the cables and the connectors. Especially the connectors due to contact corrosion. Someone mentioned in another thread that the CCU itself was very reliable. So, I decided to pull each fuse related to the CCU and clean the fuse's metal contacts with heavy grit sandpaper till very shiny. I previously had done this and it hadn't help. This time, however, I made sure that I put the fuse in and took it out and repeatedly reinserted it almost a dozen times. This helps clean the associated connectors that are in the fuse panel. I then turned on the ignition and it powered right up. Haleluah!

This simple fix should be the first thing tried by anyone working on an electrical issue of an older car.

pyramidimaging

Sorry, I forgot to mention one other thing. Thanks, StuartQ and klr10 for responding.