E46 Electric Fan Issues

Zound

///Member
So it all started with a long Sunday drive, where at the end of my journey I started hearing a whine/squeal from the engine. Opened the hood and was pretty sure it was the belt or a pulley. Decided to investigate further and after de tensioning the serpentine belt, I noticed that my belt had a small notch/wear on the ribbed side and the idler pulley bearings were shot. I then decided I'd delay the fixing to the weekend as it was a Thursday afternoon. Friday morning I drive to Varsity and I notice that the noise was gone, which was quite satisfying and gave me confidence that the car would be fine to wait till the weekend to fix the pulley and belt.

What a silly assumption!

Upon leaving varsity late on friday evening, I reverse the car and notice that the steering is a little bit difficult and that my battery light was on. After turning through one corner without power-steering I knew something was wrong and pulled over. Even before popping the hood I knew what had happened, the serpentine belt must have snapped. in 200m of driving I had one mangled and destroyed serpentine belt, a broken AC belt and an "eaten up" Mechanical AC tensioner. Had my dad tow me back home.

Id just like to point out right now that because I delayed the repair of the initial pulley and serpentine belt, I had now accumulated a parts bill for more than double what the pulley and belt would have cost!!:bangdesk:

I have now just installed the new parts (which was surprisingly easy), took about 30 minutes total for the 4 parts (AC Mechanical tensioner, idler pulley, AC belt and main serpentine belt).

Now after having driven the car for a day, I have a new gremlin:cry:

The AC system/blower will only blow warm air even with the snowflake activated. It is not even capable of blowing ambient temperature. Whenever I have "un-approved" warm air coming from the vents, I start watching the temperature gauge like a hawk. Thankfully the car never reached past the halfway temperature line and thus initially didnt assume the cooling system was responsible for my problem. After further investigation at home, I find that the electric fan is not working,at all, under any circumstances I could induce. I was able to identify faulty electric fan because the engine was un-naturally warm after its daily drive.

Has anybody got some insight into this issue? Or do I simply have to bite the bullet and replace the electric fan?

I cant test the fan motor because I dont have equipment to create a PWM signal, but I have tested the incoming harness to the fan which has power (12V).

Any help would be much appreciated.
 

OppositeLockMT

Active member
Would be interesting to get some insight into this.

After my accident 3 years ago I haven't managed to source an auxiliary fan and I've been running without one since without any issues. Does it function differently on the M54?
 

Zound

///Member
Unfortunately I have a manual, so my electric fan provides engine cooling as well as assisting the AC, so I definitely won't be driving the car until I sort it out.
 

Peter@AEW

BMWFanatics Advertiser
Official Advertiser
Have you checked the wire to the aircon compressor?
Sounds like the belt may have broken/dislodged it?
 

Zound

///Member
a1exander said:
Have you checked the wire to the aircon compressor?
Sounds like the belt may have broken/dislodged it?

I'll check that right now, thanks for the suggestion!:thumbs:
 

Zound

///Member
Okay so the AC compressor trigger seems to be firmly plugged in and unscathed by the broken serpentine belt incident. Another forum suggested that I test the fan by unplugging the sensor from the radiator outlet. The fan is supposed to come on immediately upon engine start, when AC is turned on and should run deliberately if I unplug the radiator sensor. I've tried all three of those separately and simultaneously and still the fan won't move a mm.

Also, when I turn on the AC, I don't feel any kick, and when looking into the engine bay, it doesn't seem like the clutch has engaged is stationary relative to the several spinning pulleys.

Perhaps my DME knows the electric fan isn't working and is deliberately not allowing AC operation, such that when the engine gets too hot, it will first cook the human, before it cooks the engine.

I am going to open up the fuse box and look for the relay... Otherwise I suppose I'll just have to start looking for an electric fan...:cry:
 

Zound

///Member
a1exander said:
Are you picking up resistance on the fan plug

Between which terminals should I measure it? And what kind of value should I expect to see?

Thanks!
 
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