Fan Resistor

[Louie1411]

Just replaced fan thermoswitch. Noticed that there is a fan resistor available in my parts catalog. Whatizat?? What does it do? And where is it? Should it be replaced when replacing a bad switch?

[divezic]

According to the wiring diagram, the fan resistor is used for post-shutdown cooling of the engine. When the fan is running with the engine on then the fan runs at a high speed. When the fan is running with the engine off then the fan runs at a lesser speed. The resistor drops the voltage to the fan in the engine-off cooling circuit.

Replace it if the fan does not run when the thermoswitch kicks the fans on and the engine is off. I don't believe replacing this is a matter of course when you change the thermo switch.

[PorscheG96]

There's a simple way to know when one of your resistors has gone bad [btw, there are two of them]. They are ceramic and when one of them no longer operates the other bears all the electrical load...it overheats. So what happens is you'll hear your low speed fans run until the resistor gets too hot [car on or off], then they will start running fast until the resistor has a chance to cool down. About 10 seconds later you'll get your low speed fan back but once the resistor gets too hot again you'll get high speed fans...basically, fan 'cycling.' You can tell which one is GOOD by feeling it and watching your skin melt off from the extreme heat. OR you can measure resistance across with a multimeter, this should show a value between 0.1 and 0.9 ohms if it's still working.