View Full Version : High electric radiator fan speed problem


Greg S
01-10-2008, 08:27 PM
This is on a manual 01 330Ci (which comes with only an electric fan from the factory). So I've removed the carpets, sound deadening, radio harness, door wiring, front windows, sunroof, AC compressor, lines, and canister thing. The heater core, condensor, and AC controls are still in. I've messed around with the AC controls from turning it on full heat, to full cool, AC on, AC off, everything off, and nothing seems to make a difference. The water temp gauge seems to be working as it was slowly getting up to temp(idling in the garage). The OBC ambient temp reads 57*. When I start the car the fan speed starts at low, but then as the idle lowers the fan speed picks up until it's on high(which is pretty damn fast). Any ideas?

Greg S
01-11-2008, 05:09 PM
Anyone?

thejlevie
01-11-2008, 06:43 PM
This fan may be a variable speed type using a PWM signal generated by the DME. If so you are probably stuck with how it operates.

Greg S
01-11-2008, 07:22 PM
This fan may be a variable speed type using a PWM signal generated by the DME. If so you are probably stuck with how it operates.
What does PWM stand for? I think it's somehow related to the AC removal. There's an electrical connector to the compressor that I undid, something with that?

thejlevie
01-11-2008, 08:49 PM
PWM means pulse width modulated. If that's what you have there's a speed controller in the fan that receives a PWM signal from the DME. The width of the pulses causes the fan to run faster or slower as needed. I'd guess that the DME would be monitoring radiator and engine temp to determine what speed the fan needs to run.