Erratic a/c & heater fan E46

[enterprise]

Model e46 year 2000 318iSE, 90% of the time the fan speed runs at max irrespective of the fan speed setting on the climate control unit – The Haynes manual for this model does not show all the circuit wiring for fan blower – references are made of fan limit switch and heater blower control module but no indication where these are located to allow testing to commence – any help with circuit diags/ description and location of modules would be greatly appreciated.

[1beamer]

I have also a problem with my fan on my e46 2002 318i. In my case the fan is stopping 90% of the time.
I have checked the fan control voltage deliverd by the airco control module (on Blue / Red wire on the back of the unit) and this looks OK. I mean the voltage increase and decrease when I change the fan speed from the front control buttons and when the fan stops the voltage is still there. You can do check this by switching the aico control unit with another one if you have a good friend willing to help you. I have also dismantled the air inlet to reach the fan.I've measured on the connector of the fan and there was no power.
The next step where I stopped is to find the box 126 from the techical diagram (looks like a final stage amplifier).This is the only one between the fan and the control unit. I think your case is similar.
Looks like nobody really knows where the box is located therfore I start considering visiting the dealer.

[woobiee]

this is a known problem and the most common fault is the "Final Stage Resistor" in the cooling/heating unit. the part is inexpensive but gettin to it may cost a bit more. i have this problem and i havent gotten around to it yet.

[1beamer]

Originally posted by woobiee@Oct 18 2004, 11:15 PM
this is a known problem and the most common fault is the "Final Stage Resistor" in the cooling/heating unit. the part is inexpensive but gettin to it may cost a bit more. i have this problem and i havent gotten around to it yet.

[snapback]213582[/snapback]

I have solved the dam thing.It was the final stage amplifier ( resistor it was to E36 now is an active device).It is pretty hard to get to it but after all worked.
You can buy the part from the dealer (67 EUR )and then at least you know what to look for.