I am finally going through the heating system on my 964 C4 92.
My OBT 999 diagnostic shows a fault code for the rear heat temp sensor (15).
I tested mine off the car and got about 10 kOhm at 20C and 4 kOhm at 50C. I have look for actual values without any luck.
Does anyone have./know where to find this slightly obscure info. Also, the reisistance for the fan high/low speed restistor in the air duct.
The fan seems to work OK, for instance does stay on with a switched off hot engine.

 

 

Your temp sensor seems to be fine according to your measurement readings. The rear temp sensor code might be due to an old problem or disconnected sensor in the past. Delete code and re-read to se if the fault is still there.
964 CCU with software version H00/H01 does not have any functions for actual values, only fault codes.
Cheers,
Tore