Auxiliary Fan & AC

[e30Squid]

Thanks for all of the info and quick responses...

[Brandon12V]

if the fan works when your temp gets to the 3/4 mark, then it should work when you press the a/c button. it sounds like your resistor is done since the low-speed isn't working. when the ignition is in the 'on' position, press your a/c button. If the fan does not come on, check continuity pre- and post-resistor. If you are not getting voltage post resistor, then the resistor is bad. If you do not get power pre-resistor, you have a short somewhere on the harness or one of your fuses blew. PM bimmerteck and tell him i sent ya. He helped me out a great deal when installing my aftermarket fan. He knows his shit.

[scottinAZ]

According to my ETM, there is a leg at S228 that goes to the aux fan to kick it on when the AC is enabled. My 87 sedan does this just fine, as it should. This feeds a diode in the Power distribution box that energizes K1 (normal speed relay). This is done independently of the normal fan switch that works off of temperature.

[tomwas]

My 87 325is is doing the same thing, aux won't kick on til almost in the red zone, like you it happens in slow/standstill traffic.. My tech said the fan should come on when a/c is turned on but offered no resolution to me at the time... Anyone got any ideas for this prob..... Thanks, tomwas

[e30Squid]

I have a few questions regarding the factory Auxiliary (electric) Fan and the Air Conditioning on E30's. I have seached a few times but have not found any definitive answers.

My car is a 1990 325i and the fan clutch and water pump are less than a year old. I have noticed that my auxiliary fan does not run when I turn the AC on in my car. (this is also the time when the temp gauge will start to rise a little). Actually the electric fan will not turn on until the gauge is at the 3/4 mark on the gauge (this only happens at standstill with the AC on). Other than this my temp gauge stays around the 1/4 mark.

My Questions are:

1. Should the Aux Fan run whenever the AC is running?

2. Are there connections that I should check?

3. To me it seems that if my fan doesn't kick on till the 3/4 mark then the lower temp portion of the fan switch isn't functioning properly. Could this be a resistor problem? How do I check?

Thanks in advance for any help/advice.