[phsullivan]

I have a 2006 330i, with about 120k miles.

Over the last couple of weeks, my car has been occasionally running hot, where I receive a warning to drive the car moderately to cool it down. I recently had my AC serviced and they said that my radiator/condenser fan wasn't running correctly.

When I turn on the AC the fan does not start as it should. After a few moments, it starts to spin very erratically, stopping and starting frequently and never getting up to full speed. I replaced the fan with a used one (it is hard to find a non-California emissions spec car here in the Northeast).

When I just installed it, it acted identically to my old one. I am suspicious that two random fans would fail in exactly the same way, but still function a little bit. There are no engine codes being shown, but I do not have a BMW-specific tool in order to be able to look into it more deeply like I can with Volvo.

I recently changed the temp sensor on the lower radiator hose and the water pump/thermostat at 66k (not sure if it was a failure or preventative at the time).

I had thought that the fan controller was integral to the fan. Any suggestions on where to look next?

Thank you!

[phsullivan]

Investigating more tonight, it looks like the f as n is not receiving a constant 12v on the heavy red wire at the fan connector. The ground is good though. It seems like the fan tried to moves coincided with the voltage rising to 12v, but then the voltage drops off quickly and the fan stops moving.

This leads me to think that the relay is failing, but I am having trouble finding its location. Can anyone point me to where it is?

[E92_William]

When I try searching for that on ISTA it shows me this relay. Should be for the radiator fan although there's a chance it is for the little fan that cools down the DME. It's location and number might change depending on what month and year build date your 330 is.

[phsullivan]

Thanks! I found that one and replaced it, but it didn't change anything. It turns out that it is a problem with the wiring itself. With the car running I started moving around the wiring harness going to the fall and once I found the right spot it fired right up at a normal speed.

I am guessing that I somehow fatigued or crimped a wire when I have bent it out of the way to access the radiator assembly. Most recently I just changed out the AC condenser, which meant removing the fan and radiator. When I access those parts, I usually gently lay the fan wiring harness up by the coolant tank to keep it out of the way. Something to keep an eye on for everyone else.