Radiator Fan Testing
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2004 C240 4Matic
Radiator Fan Testing
I have searched but find nothing on this specific question: At what temp should the fan come on in a 2004 C240 W203? I replaced the coolant and after topping up the level to the correct point, let the engine idle until the fan came on. Well, the fan never came on before I chickened out and shut off the engine when the temp was between the middle mark and the high (120c?) mark. In other cars the fan has always come on briefly when idling.
The car runs at a steady a little above 80c when driving. Should I start testing the temp sensor?
The car runs at a steady a little above 80c when driving. Should I start testing the temp sensor?
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
The only real way to test is with a Star & run a simulation. The fan is controlled by the ECU over CANbus to the fan controller which is on a fly lead from the fan. As long as your temp gauge is approx 80 things are fine as long as you have all the air out of the system. On your car the thermostat starts opening at approx 79 degrees.
Remember if the HVAC is on the fan will run. Fan parameters can also be changed with a Star.
Remember if the HVAC is on the fan will run. Fan parameters can also be changed with a Star.
Thread Starter
Junior Member
Joined: Oct 2014
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2004 C240 4Matic
OK. Thanks. I guess I have to be satisfied with this response. You gave me a way to test the operation of the fan. But to simulate an overheating situation when the fan would come on, I guess it can't be done except with STAR.
Thanks a lot for your quick answer.
Thanks a lot for your quick answer.
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Joined: Jun 2008
Posts: 19,942
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
If you have squeezed the hoses & got most of the air out I would just drive the car for a few weeks & it will bleed itself & might need a slight top up. Then monitor the fan behavior. I had a C240 prior to my present car. Served me very well & is now serving a friend equally well.
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Junior Member
Joined: Oct 2014
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2004 C240 4Matic
I topped up the coolant reservoir (flush was with MB blue coolant 50:50) and turned the controls to auto and sure enough the fan did come on. So I know the fan works will have to wait until I can simulate overheating on the STAR system to see if it's going to come on when overheating.
