Overheating, AUX Fan Not Operating.

AudiA38LStage1

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Hi everyone,

After sifting through a lot of information on this forum and others, I am still struggling to pin point an issue I’m having with my passenger side thermo fan not turning on, causing the engine to overheat.

Assuming the problem was the fan motor after applying 12V power to it directly and it not turning, I bought a second hand replacement and put it in, but still the fan won’t turn on with the AC like it’s supposed to and I’m still experiencing overheating. I connected direct power to the replacement fan via the battery and, nothing.

I’ve inspected the fuses on top of the battery visually and with a test light, all seem to be fine. I’ve checked the fuses on the drivers side (Although I’m not sure which one actually correlates to the AUX fan?)

Next step I tested the thermo switch for power, which it has, then I jumped the pins. The drivers side (small thermo fan) has both low and high speed, but the big fan has neither.

Have I just gotten unlucky and bought a dud second hand fan? Or could it a wiring issue in between the connector and the FCM, or the FCM itself?