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DISCUSSION => Electrical => Topic started by: pbgd3skier on August 15, 2010, 01:26:56 PM

Title: aux fan troubleshoot question.
Post by: pbgd3skier on August 15, 2010, 01:26:56 PM

Good afternoon. Been trying to get my fan going. If I directly apply 12 v to the fan I get it to run one speed. I cannot get it to run moving to the other terminal. I suspect this means resistor.

But if I jumper at the thermostat switch it pops the fuse. Is this common with  bad resistor. It won't run low speed and I suspect that's why it won't start high speed with out blowing the fuse. Reasonable?

Title: aux fan troubleshoot question.
Post by: E30_80Y on September 22, 2010, 12:41:52 PM

good question, bump. this would somewhat help me too.

Title: aux fan troubleshoot question.
Post by: DesktopDave on September 22, 2010, 02:53:47 PM

Yep, your resistor is bad.  I'd say it's shorting internally to blow that fuse.

The motor works the same either way, the resistor bleeds off power as heat to slow the motor down.  Sloppy system, but cheap & reliable.

Title: aux fan troubleshoot question.
Post by: inarticulate is on September 22, 2010, 06:10:38 PM

The fan is such an air blocker I thought I'd try running without one, since original had died. So far so good, over 2 months, engine temp stays constant and my air cond. is working better.:rolleyes:

Title: aux fan troubleshoot question.
Post by: DesktopDave on September 23, 2010, 07:08:29 AM

A lot of M42'ers have swapped in an electric Spal or Volvo fan, removing one or both stock fans in the process.