Question about 2003 Mercury Grand Marquis

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Radiator fan runs constantly

Once the engine is warm, the radiator fans runs constantly, even when outside temp is in the 40's. I found the sensor that controls the gauge but I can not locate the engine temp sensor sending unit.

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Posted on Jan 02, 2017

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SOURCE: 1993 Mercury Topaz engine running hot at high

Chec your cooling fan relays, they control the on/off

Posted on Jun 29, 2010

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SOURCE: Hi: I read your answer to

Very correct the ECT is a 2 wire thermistor,when coolant temp increases, the resistance andsignal voltage decrease,If you disconnect the sensor the fan goes on, you just trouble shooted the vehicle cooling fan switch, If anything the signal to the gauge itself may be non-op and not getting to the indicator, try this with vehicle at warm up temperature if you turn the A/C does the fan turn should if it doesnt the power juction box (fuse and relay in engine compartment should be checked, for any opeen fuses, By the way the guage information is from the PCM

Posted on May 04, 2011

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