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MG MGF Technical - engine fan

just started thr f (not used since sat as i use wifes car when on nights)when i turned on ignition the engine bay fan came on this is the first time this has happened never had it come on before even when hot any ideas anyone thanks richard
tg hardwick

Disconnecting the plug from the engine bay sensor will open circuit the loop and should disable the fan. Short circuiting the plug should start the fan. This test should narrow it down to a wiring or sensor fault.
Mike Hall

took it to work this am fan not coming on now plan to check it out this afternoon
tg hardwick

just changed fuel filter and started car fan came on again so diconnected the switch fan still running anyone had this issue ??
tg hardwick

fan not come on for four days tonight it was on again when parking only travelled four miles is it ok to drive with fan on ?
tg hardwick

Probably not great for the fan or the car. Due to the sensitivity with F cooling systems I'd want to get this sorted, or a simple(ish) problem could escalate to something much more expensive (HGF).

Sorry I can't be a more direct help.

Good luck, Russ
Russ68

>>just changed fuel filter and started car fan came on again so diconnected the switch fan still running anyone had this issue ??

When you say 'disconnected the switch', do you mean you physically disconnected the plug from the sensor in the engine bay and that the fan was then still running?

If yes, then this suggests a wiring issue somewhere. I don't have the relevant details here at work, but am fairly certain this is not routed through the ECU. Sounds to me as if there is an intermittent short circuit somewhere. As a starting point, have you checked all the wiring around the boot hinge mechanisms?

There is no way the engine bay temperature could have reached 85 deg C - the temperature at which the engine bay fan should cut in, in the four miles you travelled! (The engine bay warning light on the dash is triggered at 130 deg C). Even more reason to suspect a wiring fault I would suggest.
Mike Hall

As a PS to the above, I should just add that the ref to 85 deg applies to the VVC. For the 1.8mpi it's 75 deg C. (That's the problem with always thinking in terms of my car :o) ).
Mike Hall

yes mines a v v c not doing it again so suspect wireing fault will have to investigate when i have enought time to strip it all
tg hardwick

I would suggest a new switch. The fan is driven via the ECU and failure of the switch will cause the fan to run permanently as will disconnecting the connector from the switch as this is the failsafe mode. This is a common problem and we sell many switches through our Ebay shop Kar-Solutions ( Ebay ID onlinetb )
David Karle

Sorry my comments were for the radiator fan not the engine bay fan! Should read the threads more thoroughly!
David Karle

Engine bay fan works the same way as the rad on my MPis - disconnect the sensor to switch fan on in failsafe mode, plug it back in and the fan stops. Dieter has values for the resistances of both sensors on his site:
http://www.mgfcar.de/index.htm
Go to 'Sensoren' in the index.
Charless

just got a "tested sensor" from mgf suppliers but fan still on when i plug it in does the sensor have to be bolted on (to earth)as i have just plugged it in as my 2 yr old is running around and havent time to look in depth at the mo thanks richard
tg hardwick

just fitted i has to be bolted on. to work must need earthing, fan now off :)
tg hardwick

This thread was discussed between 12/08/2010 and 14/09/2010

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