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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 549 (Electric Cooling Fans) >> System Tests >> Test A: Excessive Fan Noise >> Diagnostic Aids

Diagnostic Aids

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

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 percent 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 in-line connector could cause an intermittent DTC. Ensure to test for poor connections and pin retention at all in-line connectors. Refer to system schematics for connector and locations. If the condition is not present, refer to INTERMITTENT OR POOR CONNECTIONS  under TROUBLE SHOOTING.