Porsche Repair: fan motor, coolant temperature sensor, continuity tester

Question
Dear Dave I own a 1987 944. My promblem is the fan motor will not shut down( after a reasonal time) after I have shut the engine off. It has run the battery down on serval occasions. I have replaced the fuses, and also the fan relay in the fuse box.This has not helped. Help! I can't drive like this. The A/C fan seems to be operating fine.

Answer
Hi Jim,

I've seen the opposite problem, where the fan doesn't come on at all... because the A/C relay has failed without anyone noticing.  In your case, I'm betting that the coolant temperature sensor is bad, essentially telling the cooling fans to keep working, and telling you to keep buying new batteries.

Try this test...when the car is cold, find the brown/white wire from a cooling fan motor to the temp sensor.  Attach one end of a continuity tester to the brown/white wire's terminal and the other tester end to ground.  At this point, there shouldn't be continuity.  Getting continuity when the sensor is reading cold means it will trigger the fan at start-up...and virtually forever.  Getting continuity means replacing the sensor.  

Let me know what you find.

Dave