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aux. fan - 300TD

My auxilary fan was not working in my '81 300TD so I tested it by disconnecting it and running a hot lead to the battery while grounding the other lead. The fan did not work. So I purchased a used fan off ebay and tested it the same way. It worked, so I installed it. I wanted to test it again and heard that if I pull the wire from the temperature switch, which is located near the thermostat, and ground the wire, the fan should run. I tryed, but nothing happened. I did see a little spark when I grounded the wire. I checked the fuse in the fuse box located on the firewall but the fuse was good. Am I doing something wrong? Is there an inline fuse somewhere? How can I check to see if the fan is working properly?

Thanks, Gary

Reply to
Gary
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The engine does NOT control the aux fan on a 123 body. ONLY the A/C works the fan. Go to the drier behind the right headlamp. See the tiny switch mounted to the top? Bridge those 2 wires with the key on and the fan should run.

Reply to
Karl

I believe there's a relay that's activated by the temperature sensor.

Reply to
T.G. Lambach

So when is the fan suppose to come on? When the engine temp reaches a certain temp or when the AC is on?

Reply to
Gary

Engine temp will NEVER turn it on. It ONLY comes on when the AC temp is too high. The ONLY temp sensor for the fan is in the top of the AC drier.

Reply to
Karl

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