Engine Cooling Fan And Clutch Description. Pontiac Sun Runner - 4WD (Canada) 1998

For 1990-2009 cars

The cooling fan is connected to the coolant pump shaft by a fan clutch. The fan clutch regulates the speed of the cooling fan revolution based on the air temperature at the clutch and provides slippage of the fan when cooling is not needed.

The fan rotates at the same speed as the coolant pump shaft when the engine is at idle, regardless of the air temperature at the front of the clutch.

Clutch slippage increases when the air temperature at the front of the clutch approaches 55°C (131°F) and the engine speed increases gradually. The revolutions of the cooling fan will not noticeably increase, even when the revolution speed of the water pump shaft increases.

The cooling fan speed becomes constant at 3,100 rpm independent of the coolant pump shaft when the air temperature at the fan clutch exceeds 55°C (131°F) and the revolution speed of the coolant pump shaft exceeds 4,000 rpm.