How should the electric fans operate?
03-28-2012, 02:58 PM
#1
Racer
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How should the electric fans operate?
It has been some time since I ran my 944 and I'm not sure if the fans are operating correctly. I have an 86 944 Turbo and neither fan turns on when the coolant temp is below the first white line, or in between the two white lines.
When the needle gets to the top white line, the high speed kicks in and I don't believe the low speed is running at this time.
However, if I shut the car off and the needle was in between the two white lines, the low speed comes on, and the electric coolant pump kicks in to cool the turbo.
If the engine was cold started, and didn't have a chance to warm past the first white line and I shut it off, I will only have water pumping but neither fan on when I shut off.
I think something is off with my low speed fan since I can't seem to get it running when the engine is on. It comes on if I shut down. If I start it again, I think I remember it staying on. When should it kick in with the engine running? It is about 50-60F today so it hasn't been hot enough for me to get to the last white line. That usually happens if it is 80F+ outside.
All my fuses are ok, and both fans do work so it can't be their motors. I am not sure if my symptons are of resistor problems, sensor someplace or the relay. I have read there are 4 relays but I only see the one big silver relay that takes two spots in the fuse box.
When the needle gets to the top white line, the high speed kicks in and I don't believe the low speed is running at this time.
However, if I shut the car off and the needle was in between the two white lines, the low speed comes on, and the electric coolant pump kicks in to cool the turbo.
If the engine was cold started, and didn't have a chance to warm past the first white line and I shut it off, I will only have water pumping but neither fan on when I shut off.
I think something is off with my low speed fan since I can't seem to get it running when the engine is on. It comes on if I shut down. If I start it again, I think I remember it staying on. When should it kick in with the engine running? It is about 50-60F today so it hasn't been hot enough for me to get to the last white line. That usually happens if it is 80F+ outside.
All my fuses are ok, and both fans do work so it can't be their motors. I am not sure if my symptons are of resistor problems, sensor someplace or the relay. I have read there are 4 relays but I only see the one big silver relay that takes two spots in the fuse box.
03-28-2012, 10:02 PM
#3
Rennlist Member
Sounds like something is wrong. You should get low speed fan operation when the temp needle is on the first white line. The coolant pump is a different system, so not really relevant to your fan operation. Could be a number of things, including the thermoswitch in the radiator, relays, etc. It's a fairly easy system to diagnose fortunately. Clarks-garage has a full diagnostic plan set out here:
http://www.clarks-garage.com/shop-manual/cool-01.htm
http://www.clarks-garage.com/shop-manual/cool-01.htm