The only thing i know for sure about the aux fan is that it seems to draw a lot of amps for the amount of air it moves.
E30 aux fan resistor.
There are two different resistors listed for e30 s the bosch ceramic and the magna plastic encased.
I ve confirmed the resistor is bad so the fan doesn t run.
The aux fan should activate.
These instructions are for the bosch resistor pictured below on the right.
17 40 1 373 177 bosch ceramic aux fan resistor 64 12 1 388 069 magna black aux fan resistor.
Fan stopped on my 87 325ic causing my air conditioning to not work correctly.
Non bmw fans have also been fitted.
E30 aux fan questions.
The fan should run on low speed when the a c is running and on high speed if the engine is getting close to overheating.
The high pressure reading reaches 425 then the high pressure switch shuts down the compressor.
In reading all the posts on the two speed fan i ve learned that the only time the fan runs on the high speed is when the radiator high temperature switch.
Once the temperature reaches a certain dangerously warm level that the engine driven fan doesn t seem to be compensating for.
The auxiliary fan resistor is in need of replacement when the auxiliary fan does not operate at low speed.
When the ac is on.
Remove the front license plate if present and remove the 2 mounting screws holding the resistor bracket to the aux fan assembly.
These instructions are for the bosch resistor pictured below on the right.
The e30 m3 or otherwise a c fan is the same fan as used on the m3 that does not have a c.
E30 aux fan resistor replacement and the two different e30 auxiliary fan types rts your total bmw enthusiast.
If you get a successful conversion in place i d be very interested in knowing which spal model you use.
I noticed in the bentley manual the fan should come on at one of two speeds once the car temperature is a certain level.
If you your aux electric fan works on high speed but not on low speed your resistor is likely burnt out.