Electric Fan Problem

[macninja99]

i have a 2002 smg m3 conv and when i turn the car on the electric ac fan comes on and spins like crazy and will not turn off -

i have repalced the sensor in the hose- no difference
pluged a new fan -no difference
changed the little black box by the radiator- no difference

upper hose gets real hot - lower hose stays cool- thinking thermostat ??
rad colant is full
the clutch fan the way it works when the car gets real hot the clutch fan stiffens up and spins faster -mine just spins cold or hot i can still stop the fan clutch with my fingers --any ideas??

macninja99@yahoo.com

[Dirty_Tool]

Originally posted by macninja99@Dec 15 2004, 10:32 PM
i have a 2002 smg m3 conv and when i turn the car on the electric ac fan comes on and spins like crazy and will not turn off -

i have repalced the sensor in the hose- no difference
pluged a new fan -no difference
changed the little black box by the radiator- no difference

upper hose gets real hot - lower hose stays cool- thinking thermostat ??
rad colant is full
the clutch fan the way it works when the car gets real hot the clutch fan stiffens up and spins faster -mine just spins cold or hot i can still stop the fan clutch with my fingers --any ideas??

macninja99@yahoo.com

[snapback]251908[/snapback]

The engine control module (DME) controls the aux fan on your model. The fan receives a constant power via fuse #37 a 50 amp fuse and ground is supplied via the DME. The BMW is using the radiator outlet temp sensor as its input for deciding whether or not to turn the fan on. So unfortunately since it sounds as if you have already replaced this sensor the DME may be faulty. By any chance do you have hardware to clear any faults which have been set? I think if the outlet temp sensor fault is stored in the DME it may be causing the DME to keep the fan on. try clearing faults or if you have the equipment reprogramming the DME.

As far as the Tstat is concerned it too is electronically controlled and should be storing faults if faulty, so step 1 should be reading faults out of DME and clearing if possible then rechecking.

Good Luck,
DT

[grtmoby]

Originally posted by macninja99@Dec 16 2004, 08:32 AM
i have a 2002 smg m3 conv and when i turn the car on the electric ac fan comes on and spins like crazy and will not turn off -

i have repalced the sensor in the hose- no difference
pluged a new fan -no difference
changed the little black box by the radiator- no difference

upper hose gets real hot - lower hose stays cool- thinking thermostat ??
rad colant is full
the clutch fan the way it works when the car gets real hot the clutch fan stiffens up and spins faster -mine just spins cold or hot i can still stop the fan clutch with my fingers --any ideas??

macninja99@yahoo.com

[snapback]251908[/snapback]

In addition to the DME getting the water temperature to operate the fan it can operate it as well if it detected a high pressure in the A/C cycle.


I had a case like this and here is my recommendation on how to try to solve it:

1- Do a battery rest by removing the negative cable of the battery for 10 minutes and then reconnects it. This will clear the DME faults if any is there.
2- remove the plug of the sensor on the radiator outlet and see if this will lower the fan speed. This is to be done while engine is running and wait after plug removal for at least 1 minute. If nothing happens, proceed to step 3.
3- Remove your A/C panel and disconnect the plugs in there, all of them, and see if the fan speed gets lower. If it lowered, then most probably you have a defective A/C pressure sensor (this one fit on the dryer bottle) or the 5V supply going to is lower than 5V.

Tell us how did it go....

[macninja99]

[fixed the problem it was something stupid the ac dryer tank has a sensor on it it was unplugged