How exactly does the stock radiator fan work (pics inside)
hmph here BTW
Mar 8, 2011, 11:19 AM
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The box works like this:
it takes a signal from your coolant temp sensor on the head, near the thermostat, figures out if your car is moving or not and switches the engine fan on slow speed only at 92 deg C (in a VII) if the temp gets to 97-98, then both fans come on at high speed until temps are less than 91 deg C.
(I live in Trinidad and it gets to 32-34 deg C here every day)
if you turn on your AC it bypasses this controller and puts on the fans on high speed regularly and the engine temps hover around 85-90 de C.
If you bypass the box and run the fan on all the time the following will happen:
You will lose power due to parasitic drag on your alternator.
Your battery and Alternator will not last as long as they should
Mileage will decrease.
Your fan may not last very long either. On a cool morning with no stops for traffic in my 30 min commute the fans may never even come on. Now imagine the fan being on all the time, it puts much more wear on the fan.
lastly, the car will actually run HOTTER at highway speed that if the fan were cutting out and coning on as it should.
it takes a signal from your coolant temp sensor on the head, near the thermostat, figures out if your car is moving or not and switches the engine fan on slow speed only at 92 deg C (in a VII) if the temp gets to 97-98, then both fans come on at high speed until temps are less than 91 deg C.
(I live in Trinidad and it gets to 32-34 deg C here every day)
if you turn on your AC it bypasses this controller and puts on the fans on high speed regularly and the engine temps hover around 85-90 de C.
If you bypass the box and run the fan on all the time the following will happen:
You will lose power due to parasitic drag on your alternator.
Your battery and Alternator will not last as long as they should
Mileage will decrease.
Your fan may not last very long either. On a cool morning with no stops for traffic in my 30 min commute the fans may never even come on. Now imagine the fan being on all the time, it puts much more wear on the fan.
lastly, the car will actually run HOTTER at highway speed that if the fan were cutting out and coning on as it should.
Well I guess I could chime in on this. I work for Bosch Automotive and do testing with radiator fans and motors so yea...
I'm not sure exactly about the one on our cars (lancers alike) but I believe its a PWM, pulse width modulator that basically has a bunch of high current transistors that allow it to regulate the speed of the radiator fan at any given time. So it takes the 12v going in and runs it through the transistors at a high switching frequency allowing for the ECU to control what speed the fan spins at. Technically if you bypass it the fan would just constantly stay on at max speed.
Keep in mind this is based off the Bosch FCM (Fan Control Modules) that I've dealt with...
Hope that helps...?
I'm not sure exactly about the one on our cars (lancers alike) but I believe its a PWM, pulse width modulator that basically has a bunch of high current transistors that allow it to regulate the speed of the radiator fan at any given time. So it takes the 12v going in and runs it through the transistors at a high switching frequency allowing for the ECU to control what speed the fan spins at. Technically if you bypass it the fan would just constantly stay on at max speed.
Keep in mind this is based off the Bosch FCM (Fan Control Modules) that I've dealt with...
Hope that helps...?
I would like to remove this control box but sounds important in a DD.
Was thinking you could use the signal wire from the ECM to trigger a relay to the fan?
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