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bmwrus
09-05-2008, 06:49 AM
what is this auxiliary fan for, and could it cause a slight elevation in temp or is it just for when using the AC? and if aux. fan is good is it normal for that sensor to just stop working or could it be something else...

any input will be highly appreciated, since i don't:confused: know what else it could be?

SleepyKat
09-05-2008, 08:18 AM
The aux fan is both for a/c and help flow air thru the radiator. The aux fan start when the A/C is on when you start the car. If not then it's the ballast resistor (an those definitely can go out) Are you referring to the "sensor" as the Radiator/Aux fan switch on the side of the radiator that turns on the fan at low speed 91deg C then high speed if the coolant temp goes to 99 deg C? Yes those can go out, not common but not rare, cost about $25. You can also get a switch with a low setting as well.

bmwrus
09-05-2008, 11:04 PM
Yes the one on the side of the radiator. So if i turn the ac on even if its not charged and it does not get cold it should turn that aux fan on right when sitting and idling for a while?

SleepyKat
09-06-2008, 02:15 PM
I would not know what happens if your a/c is not charged. I would guess that the aux fan would not turn on because the compressor would not turn on and the aux fan will not turn on until the radiator heats up at which time it is assisting the clutch fan to move air thru the radiator( at about 91 deg C). if you A/C is on when you turn on the ignition the fan should turn on at low speed. If not but it works at high speed then it is your ballast resistor (located on the side of the fan).

bmwrus
09-07-2008, 09:55 AM
yeah i found that little article on the web on how to change it if its only running on high but mine is not running at all i had to hook it to the battery to make it work and test the motor on the fan and it came on , so i am not sure where to go from here i have no idea how to chase down a electric problem going all the way to the fuse box... you said something about the fan coming on at 98c is that the temp inside the radiator or on the outside, also what is the normal operating temp on the engine or for the water cycling through it any idea...

SleepyKat
09-07-2008, 01:03 PM
If the fan works, my first check would be the 2 fuses fuse 25 (30 amp) and 29 (7.5 amp) I think that's the ones), by the firewall driver side, then the 2 relays the other box same side.. If you A/C is not charged then the aux wouldn't kick on and the compressor wouldn't either...is there a leak in the system?...charging the system is fairly easy if you just need a top off.. ..... the 98deg C is in the radiator. I hope it is not outside as death valley doesn't even get near that temp..oo that would be too hot Note 98 deg C is about 208 deg F. Well, in TX at 36degC/97DegF, I kind of expect my radiator temp at about 98degC/208F or higher as I tend to sit in traffic or high speed. I'm not sure your ambient temp is in Washington (state?). Radiator coolant mix has a higher boil off rate than water.

bmwrus
09-07-2008, 08:15 PM
man I am from Austria and feel dumb as hell for even making that mistake, yes we would be like jerky with that heat, I am now in Washington and it does very hot.. maybe 90F but have not seen that in a long time... I did check all my fuses and relay and dont know what to do next, i was told to just run a switch into the dash but no way not going to ghetto rig it like that, i will just have to hunt it down, and the A/c i cant find anybody that will top it off since its the old r 12 freon and illegal so if i want to fix it i was told i will need to retrofit it for 400.00 $ i am not doing it ...