Heater not working on any speed

[mcdougal]

Edit 4/4
I was able to test the blue wire in this photo and determine that it has zero voltage with the keys in the on position and goes to 12v when the fan switch is turned on. It reads zero voltage when the resistor is unplugged.

Is this telling me that (a) my resistor is ok and I probably have a bad fan, (b) my resistor is bad although this makes no sense to me, or (c) something else that I'm not understanding?



Here is the wiring diagram.



End edit.

My heater fan/blower is not turning on on any speed. The a/c and recirculating switches are both working and fuse 20 is getting power. Any suggestions?

How do I go about testing the blower motor to make sure it is working? I think what I'm supposed to do is run a wire from fuse 20 to the blue wire that comes off the back of the blower speed control (which provides power to to the blower motor) but I'm not sure.


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[pandaboo911]

Probably your blower or resistor.

Incase you need it: http://www.r3vlimited.com/board/showthread.php?t=348412


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[dnguyen1963]

Not the resistor. Your blower should still work at the highest setting with a dead resistor. If your fuse gets power then the power should get to your blower unless the wire is broken or not making contact with the motor. Apply a direct 12V to the motor to see if it runs.

[pandaboo911]

Not the resistor. Your blower should still work at the highest setting with a dead resistor. If your fuse gets power then the power should get to your blower unless the wire is broken or not making contact with the motor. Apply a direct 12V to the motor to see if it runs.

Common misconception. My blower did not work on any speed until after I cleaned the resistor contacts and thermal switch.

If the thermal switch fails it will not turn on the blower even on max speed.


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[mcdougal]

Common misconception. My blower did not work on any speed until after I cleaned the resistor contacts and thermal switch.

If the thermal switch fails it will not turn on the blower even on max speed.


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Is the thermal switch at the same location as the resistor?


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[mcdougal]

Tonight I verified that the switch is sending voltage so I guess the next step is to test continuity between the switch and the blower motor. If there is continuity and the blower motor works when I jump it that means the resistor is bad, right?


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[mcdougal]

Bump with edit


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[pandaboo911]

Just get in there, pull the resistor, clean the contacts and thermal switch with a file, and test it.

Either way you will have to get in there to replace something


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[mcdougal]

Heater not working on any speed

I pulled the resistor and cleaned it and it didn't make a difference. Is the thermal switch attached to the blower? Google images is only showing a temp sensor in the engine bay when I search for "e30 thermal switch."

Seems like the blue wire getting power with the resistor in place should be telling me something.


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[pandaboo911]

The thermal switch is on the resistor. It's the small sprung contact that runs diagonally under the resistor coils. Carefully file the pad under it and the contact, you can also bend it slightly to restore tension.

Spin the fan by hand to check if it's seized. You can also check the condition of the brushes based on how far the wire is down the brush slot. Take a look at my thread for details.


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