yoni_d

Hi guys,

I am starting to "debug" the CCU unit on my 1980 928. I noticed the following:
1. There is no temperature control. Once I set the lower lever to "auto" and slightly move the temp lever to the right the heater is at full. The A/C is on but there is either cold or hot - not in the middle
2. When I move the lower lever to "defrost" (most right position) it works as expected - A/C is on +full fan speed + heater at full

The fact that I have only cold or hot indicates that one of the temp sensors is bad or there might be another reason? If its the temp sensors, how can I check them?

Thanks!

Alan

These are classic symptoms of the temp loop being open circuit. Most likely is the external sensor wiring under the (LHD) drivers side headlamp. I'd visually inspect that area first. It is highly unlikely it is anything else since your mixing flaps can work properly (at least to the extremes). I'd suspect the wiring not the sensors - (though the external sensor could just be missing - that happens too often, usually due to a PO messing with the alt cooling hose).

Alan

yoni_d

Thanks Alan - I will have a look!