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Registered
Join Date: May 2004
Location: Northern VA
Posts: 315
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Heater fan won't come on
I did a search but didn't find anything relevant...
Recently I replaced the heater blower motor since the old one was shot. Right after I replaced it I connected the switch and it worked fine, but then other things on the car took precedence and I just let it sit. Now that everything else is back together and working, the heater fan doesn't come on from the switch... First things, I checked the fan itself with 12V straight to it, came on no problem. Then I checked the switch with a continuity checker, and it seems to be working normally. With each click the continuous circuit moves one pole, with a constant ground. I also swapped in a spare audi switch my neighbor had (exactly the same) with no change. Then I checked voltage at the plug that the switch goes into, and I got a 9V drop between the ground and each of the poles. Is 9V normal? Is there a rheostat that brings it up to 12V before the fan? Anyway, I also checked the fuse, it looks good. Other than a broken wire (unlikely and a nightmare situation), what could be the problem? What else should I check?
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1983 944 with S2 motor, trans, suspension and exterior -- crunched parts car 1987 944 -- soon to be 1987 944S2 |
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12-22-2004, 08:48 AM
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Join Date: Jun 2003
Location: Phoenix, AZ
Posts: 1,327
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you need to check the fuse with an ohmmeter or try a known good one.
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87 951, K27/6, Almond Beige, 17" Turbotwist 87 944S, alpine white, 5sp died a violent death 84 944, silver/brown, auto, gone but not forgotten "may the force be with you" |
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12-22-2004, 09:51 PM
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Join Date: May 2004
Location: Northern VA
Posts: 315
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Checked the fuse, it's good.
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1983 944 with S2 motor, trans, suspension and exterior -- crunched parts car 1987 944 -- soon to be 1987 944S2 |
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12-23-2004, 06:46 AM
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There is a small bi-metallic strip (temperature sensing device) that is part of the resistor block which gets corroded and prevents the fan from working. This bimetallic strip is providing thermal overload protection for the motor.
The resistor block is located on the fan under the plastic cowling in the engine bay.
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1993 964 C2 still makes me smile Retired and work as needed as a pain in the **s. |
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12-23-2004, 07:09 AM
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Join Date: May 2004
Location: Northern VA
Posts: 315
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I checked the resistor block and am getting reasonable values for each resistor...I'm not sure what part of it is the bimetallic strip. Also, doesn't position 4 bypass the resistor entirely?
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1983 944 with S2 motor, trans, suspension and exterior -- crunched parts car 1987 944 -- soon to be 1987 944S2 |
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12-23-2004, 07:23 AM
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Registered
Join Date: May 2004
Location: Northern VA
Posts: 315
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Found the problem. Relay #3 (A/C) was corroded on its winding pins. Cleaned the corrosion off and everything works OK.
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1983 944 with S2 motor, trans, suspension and exterior -- crunched parts car 1987 944 -- soon to be 1987 944S2 |
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12-23-2004, 07:56 AM
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911
