KyleB

Hey everyone, would like some input. I think my fan has bit the dust on my '04 530i. The fan is controlled via PWM signal from the DME, and the fan apparently has a control unit inside of the motor (this is why it costs $700+).

I first noticed a while back that my A/C was weak unless the car was up to highway speeds. I have confirmed that when I start up the car cold, engage A/C, the fan DOES NOT come on at all (it should).

I connected the car to INPA and first ran through all three test programs. The fan will spin at 15%, 50%, and 90% per each test program, but it will only spin at these speeds if I force it to with INPA. I drove the car for about 1.5 hours yesterday morning and monitored the fan speed, it never went over 11% even sitting at a traffic light with ambient air temps near 90.

My thoughts are that the control unit portion of the fan motor has failed and isn't turning the fan motor on as it should.

Anyone else care to chime in before I bite the bullet and buy a fan?

thanks

twh

Seems to me that if you can force it with INPA, that the fan itself is fine.

KyleB

well, the motor portion of it is fine. It's the control unit portion of it that I believe has failed. It only spins up to the higher speeds if I force it to with INPA. On its own, it won't spin past 11%. I don't suspect the coolant temp sensor, because I just changed it last year with an OEM part. Everything I've checked and everything I've read about leads me to suspect a failed fan motor. It is the original fan from 12+ years ago.

I have an E82 that uses the same electric fan setup as the E60, and the fan is definitely operating at multiple different speeds the way it is supposed to, including turning on immediate at startup when A/C is called for. I've done a lot of reading over on the E90 boards, and fan failures seem to manifest themselves the way mine is.

twh

This is the key - if INPA tells it to run fast, it runs fast. That means that everything involved in getting the fan to run fast works. All the PWM stuff and the fan and fan motor and all the electronics involved in rotating the fan at any speed works.

My first thought would be that someone isn't telling the fan to run fast. That's the problem. You proved that the fan can do it with your INPA test. The problem is the car isn't deciding that the fan needs to run fast, not that it can't run fast.

BostonJon

Well said. Sounds to me like your problem is upstream of the fan. Maybe the climate control module?

KyleB

it's a SUPER simple circuit. It literally goes: ECM--->final stage unit a.k.a fan assembly. that's it, and I seriously doubt I have a bad engine control unit. There's a 60 amp fuse in the glovebox for the fan, it's good. that's literally all that's in the circuit.

I would suspect the compressor, but as soon as I get moving A/C cools right back down like it should. If you sit at a traffic light for more than 60 seconds, A/C starts blowing warm air again. That tells me the compressor is fine and I have an airflow across the condenser problem (fan).

coolant outlet temp sensor (the one on the lower radiator hose) is new, so that rules out a bad sensor


The fan is supposed to spin up to 20% immediately at startup, turn off, and then operate as instructed by the ECM. Mine does none of that. It will spin at no more than 11% once the engine is up to temp. turning A/C on and off has no effect (it should).

I'm going to noodle on this a little bit more, and then probably put a new fan in the car and see what that does. I'm pretty sure the final stage unit in the fan housing is shot, but I could be wrong. Thanks again for everyone's input. I'll update this thread as I go.

DanielFD

subscribed. never thought the fan had a control unit. Maybe you coded something on the ECM or IHKA by accident. Its worth resetting those and trying.

KyleB

yea, it's basically the final stage unit for the fan motor, and it's all integrated into a single fan assembly. if you look at the wiring diagram for the fan circuit it goes like this:

ECM ----- fan


no relays, no outboard 'fan control unit', etc.

twh

There is some input that helps decide what speed the fan should run that isn't working right.

Have a look at some of these documents. Maybe you'll find something.

https://drive.google.com/open?id=0B1...G9xSTVEdVFPQlU

KyleB

thanks, im at work but ill take a look when i get home. Theres four or five inputs listed in Bentley that determine fan speed. i cant remember them all, but I know theres coolant outlet temperature, AC system pressure (compressor), and a couple more.

BTW I notice you're from NoVA. I lived in springfield for about 20 years before I moved down here in 2006.