Excessive Fan Noise

Excessive Fan Noise

Circuit Description
The electro-viscous clutch is controlled by the PCM. The PCM controls a solenoid that regulates a fluid pressure that controls slip of the fan clutch. Internal to the fan is a centrifugal fluid pump, solenoid, hall effect sensor, valve lever and a hydraulic fluid. There is two chambers for the fluid, these two chambers are separated by a valve lever. The first chamber is the storage chamber, which holds excess fluid. The second chamber is the working chamber. As the pressure of the fluid is increased in the working chamber the amount of slip the fan has is decreased. The position of the valve lever is controlled by an electric solenoid.

Diagnostic Aids
^ Turning off the engine when the cooling fan clutch is engaged, the cooling fan clutch will be engaged at engine restart. This may cause an excessive noise concern. This is a normal condition.
^ If the engine is turned off for an extended period of time, usually over night, the hydraulic fluid may fill working chamber and cause limited slip at engine restart. This may cause the excessive noise condition. This is a normal condition.
^ To engage the cooling fan clutch, it can take up to 2 minutes for a 100% command with the engine at 2000 RPM. The lower the engine speed, the longer it will take the cooling fan clutch to engage.
^ To disengage the cooling fan clutch, it can take up to 2 minutes with the engine at 2000 RPM. The lower the engine speed, the longer it will take to disengage.
^ In lower ambient air temperatures the cooling fan clutch will engage in less time, however it will take longer to disengage.
^ An inline connector could cause an intermittent DTC. Ensure to test for poor connections and pin retention at all inline connectors. Refer to system schematics for connector and locations.
^ If the condition is not present, refer to Testing for Intermittent and Poor Connections.

Test Description
The numbers below refer to the step numbers in the diagnostic table.
2. There should be no binding or increased resistance as the cooling fan clutch is rotated.
4. The cooling fan noise should increase as the cooling fan clutch engages. It can take up to 2 minutes for full cooling fan clutch engagement. If cooling fan clutch is previously fully engaged, then there will not be a noticeable change in cooling fan noise. Compare noise to a known good vehicle. If fan noise is louder than the known good vehicle, then answer Yes.
5. In the previous step the cooling fan clutch was fully engaged. This step tests to ensure that the cooling fan clutch will disengage. A noticeable noise difference should be heard between a fully engaged cooling fan clutch and a disengaged cooling fan. The cooling fan clutch is completely disengaged when the excessive fan noise is not heard.
6. This step clears DTC that were set during previous steps. Test driving the vehicle will attempt to set DTC not previous found in the Engine Cooling Diagnostic Check. If no DTC is set the condition is normal operation of the cooling fan.

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Excessive Fan Noise