A/C and fan at front of radiator question... - The Unofficial BMW M5 Messageboard (m5board.com)

plisken · 28th March 2004, 11:35

I have been advised in these forums that when the A/C is on, the small fan at the front of the radiator comes on, I have observed this and it does indeed seem to be the case. What I also notice though, is that it then goes off after a period of time, then again comes back on, when this happens you can feel the revs drop slightly, which I fully expect.

My question here, is, shoudl this go off and on, when the A/C is running, or is it an indication that my A/C is going off and on.

My A/C seems to be working fine, well at least it does produce cold air.

Thanks

TBrown · 28th March 2004, 20:55

The a/c compressor cycles so that the evaporator doesn't freeze up. so it may be going off and on with the compressor cycles. You can watch the compressor and see when the clutch cycles.

dronfieldm · 31st March 2004, 23:17

I've just asked my BMW Trained Technician friend, who says that the fan trips in and out in order to cool the aircon pipes and hence help regulate the pressure in the system.

As the pressure changes, the fan trips in and out, so, as thought, it should not be on all the time.

Hope this helps.

All the best
Mark

mike707 · 1st April 2004, 06:50

The aux/pusher fan cools the refrigerant that goes through the condenser to remove the heat that was absorbed in your car through the evaporator (I believe it's right behind the heater core in E34's).It is normal operation for the fan to turn on then off. The aux fan will also come on when your car is at idle and it reaches it's full operating temp. It just aides in pushing air through the radiator, kinda helping out the fan. You may also hear it when in stop and go traffic. BMW has switched to a dediicated electric fan (finally) on the N62 engines and on the newer models.

plisken · 1st April 2004, 10:52

May have to check, as I have only seen it come on and off when the A/C is running...

Simply a matter of allowing the car to idle for 10 minutes or so...