The aux fan in my E36 M3 is not turning on. I checked the fuses and everything is good. I've seen it barely kick over a few times in the past few days plus it rotates "forward" easily but has resistance when rotating "backwards" when it's supposed to be on(AC turned on), so I am 99% sure it is a dead motor(versus a wiring/sensor issue).


A new fan is expensive, so is it possible to just replace the motor with another used one? I've seen a few motors on eBay and whatnot, but I can't get any clear info on if it's possible to just replace the motor. The fan blades don't really seem like there is a nut or anything holding them on.

When the compressor clutch is powered, so is the low speed circuit of the auxiliary fan. That means it could be that the resistor is faulty.

Does the fan spin freely in both directions when the engine is off? Does it run on high speed only when you jump the thermoswitch connector on the right side of the radiator? Is there voltage coming from the low-speed fan relay when the fan is supposed to be on? If yes to all, replace the resistor.

maybe do an electric fan retrofit. I have one for sale in the classifieds. I can get the info for you.

The aux fan in my E36 M3 is not turning on. I checked the fuses and everything is good. I've seen it barely kick over a few times in the past few days plus it rotates "forward" easily but has resistance when rotating "backwards" when it's supposed to be on(AC turned on), so I am 99% sure it is a dead motor(versus a wiring/sensor issue).


A new fan is expensive, so is it possible to just replace the motor with another used one? I've seen a few motors on eBay and whatnot, but I can't get any clear info on if it's possible to just replace the motor. The fan blades don't really seem like there is a nut or anything holding them on.

You can do a quick check on your aux fan motor. Disconnect the plug from the sensor on the side of the radiator. There are 3 pins in a triangle inside the plug. The center pin is common and the 2 outside pins are low speed and high speed. Jump between the common and each of the pins, one at a time to see if each of the speeds is working. Hope this helps.

John B.

Thanks for the responses.

Answers -

The fan seems to spin with no resistance when off, but with the AC on it has resistance spinning in "reverse."

I have jumped the connector, and the fan did nothing.

if you jumped it and it didn't start up then to me it sounds like a bad motor.

i used a 16" universal fan (removed the plastic guard) from an auto store for $65 and modified the stock aux fan shroud to fit the universal fan. it has been working great and I'd do the same thing again if the fan broke down the road, can't beat the price.

Did you jump the switch with the ignition on? Did you try both circuits like Cajunroadster suggested? If so, there's a good chance the fan is bad. But maybe not, and you would feel bad if you replaced a perfectly good fan. So check for voltage at the fan connector, at the bottom of the shroud.

Disconnect the fan connector, ground the voltmeter at the brown wire on the harness side of the connector, jump the thermoswitch on the radiator, and check for voltage at one of the other two wires in the fan connector. Then jump the other circuit at the switch and check for voltage at the other wire at the fan connector. If you have voltage at both wires, you know those circuits and the ground are ok, and the motor is faulty. If you don't have full battery voltage at one or both wires, something else is wrong and replacing the fan won't fix it.

Gotcha - guess I'll pull off the underpanel after I finish up the turbo install on my Nissan.

When I tried to jump the fan, the car was running and the AC was on.