How to Test a Fan Clutch on a Chevrolet

by Allen Moore
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A fan clutch is the assembly that your engine cooling fan rides on and that tells the fan when to turn on and off. A central core, which locks and unlocks based on the temperature, allows the fan to spin with the engine crankshaft or freewheel on its own. A bad fan clutch can leave you without an operational fan, which in turn prevents the proper amount of air to cross through your radiator core. Without enough air over the radiator core, your engine can overheat in a matter of minutes. If you determine your fan clutch is faulty, replace it immediately.

Step 1

Put your safety glasses on and climb under the vehicle with your flashlight. Look up at the underside of the fan clutch and inspect for any leaks from the clutch itself. Climb back out when you are done.

Step 2

Raise the hood, with the engine off and cold. Reach in and spin the fan blade by hand. If it continues to spin freely for more than five turns with no signs of drag, you have a bad fan clutch.

Step 3

Start the engine and look down at the fan. The fan should be still or barely revolving until the engine warms up. When the fan begins to turn at engine speed, move to Step 4.

Step 4

Push the piece of cardboard down into the spinning fan, being careful to never get your hand or any part of your body or clothing anywhere near the fan blades. It is best to do this from the front of the vehicle, instead of the side, so that any pieces of cardboard knocked loose will not fly up at you.

Step 5

Watch the fan to see how it reacts to the interference from the cardboard. If the fan begins to slow down, or comes to a halt altogether, your fan clutch is bad and should be replaced. If not, your fan clutch is working properly as long as you have seen the fan cycle on and off during this inspection.

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