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Why Won't a Radiator Fan Turn On?

by Richard Rowe

A car's electric cooling fans are responsible for ensuring air flow over the radiator at low speed, and failure will almost always cause overheating while in traffic. Fortunately, these systems are fairly easy to diagnose in the event of failure.

Blown Fuse

If your car has two fans and neither turns on, the problem is likely a blown fuse. The fan fuse can be located in either the in-cab fuse box or the under-hood box.

One Fan Engagement

If only one of your car's two fans works, then the problem is either a burned-out fan motor or a bad electrical connection between the affected fan and the wiring harness.


If your fans do not engage and the dashboard temp gauge reads normal, then the thermostat sensor is bad. A bad sensor will tell the car that everything is normal while the engine overheats.

Seized Motor

If your car's fan does not turn freely by hand when the engine is off, then the fan motor is seized and needs to be replaced.

Low Voltage

Fans may fail to engage if the car's system voltage is too low, as might be the case with a failing alternator.

About the Author

Richard Rowe has been writing professionally since 2007, specializing in automotive topics. He has worked as a tractor-trailer driver and mechanic, a rigger at a fire engine factory and as a race-car driver and builder. Rowe studied engineering, philosophy and American literature at Central Florida Community College.

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Photo Credits

  • Image by, courtesy of Peter Morgan