Saturday, February 25, 2012

How to replace engine Cooling Fan Switch?


Cooling Fan Switch Operation:

The cooling fan switch on electric fans monitors coolant temperature signals from the engine control computer. When the engine is cool, the switch opens to keep the fan from spinning. When engine is warm, the switch closes to turn fan on for cooling.

See below how the cooling fan looks :---


Before replacing cooling fan switch .Inspect and tst it.

Inspect the cooling fan switch's wires and connections. Cooling fan switch problems are often caused by faulty wiring or loose or corroded connections rather than the failure of the switch itself. If the wires or connections are bad, replace them. If you think the switch is defective, it should be tested.
Also listen for a pinging noise, failed cooling fan switches can cause pinging when the engine is overheating.

Test :--
When testing a cooling fan switch, first test it with the engine cold, then test it when the engine reaches a specified temperature. Check your vehicle's service manual for more directions.
To check a switch, disconnect the connector at the switch. with an ohmmeter, check for continuity between the terminals of the switch with the switch moved to the on position and to the off position.
The continuity through a switch can be checked with an ohmmeter. With the switch open, there should be infinite resistance. With the switch closed, there should be zero resistance.
With the switch off, there should be no continuity between the terminals. With the switch on, there should be good continuity between the terminals. If the switch is activated by something mechanical and doesn't complete the circuit when it should, check the adjustment of the switch. (Some switches are not adjustable.) If the adjustment is correct, replace the switch. Another way to check a switch is to simply bypass it with a jumper wire. If the component works when the switch is jumped, a bad switch is indicated.
Voltage drop across switches should also be checked. Ideally, when the switch is closed there should be no voltage drop. Any voltage drop indicates resistance and the switch should be replaced.

Replace cooling fan switch :--

Because of the variations of electric cooling fan systems, manufacturers' schematics and specifications must be consulted for troubleshooting and repairing any particular year-model car.

CAUTION
Some fan motors will start, and run, without warning even though the ignition switch may be in the OFF position. Therefore, extreme caution should be exercised when working under the hood of a vehicle equipped with an electric cooling fan.

To replace the switch:

Disconnect the negative battery cable.
Unplug the cooling fan switch.
Then, unscrew it.
Reverse the removal procedures to install the new part.
Connect the negative battery cable to the battery.

This will help
Thanks.

See below latest solved car problems :---







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