GM Service Manual Online
For 1990-2009 cars only

Cooling Fan Description


Object Number: 11643  Size: SH

The electric cooling fans aid air flow through the radiator. Electric motors attached to the radiator support drive the fans. Coolant temperature activates the fans. A switch can activate the fan motor when the air conditioning compressor is operating. In order to prevent overheating, the Powertrain Control Module (PCM) regulates the voltage to the cooling fan relay, which activates the fan when the engine coolant temperature exceeds 106°C (220°F).

Electric Cooling Fans

Electric motors drive the engine cooling fans. The motors are attached to the fan shroud at the rear of the radiator. The left and the right fans have 5 blades, and these are 299.0 mm (11.77 in) in diameter. The fans have two speeds, high and low.

Cooling Fan Relays

The engine cooling fan relays provide the high current necessary for the cooling fan motors based on a low current signal coming from the Powertrain Control Module (PCM). This signal is a function of the following inputs:

    • A/C condenser pressure
    • Coolant temperature
    • Oil Temperature
    • Throttle position
    • Vehicle speed
    • Engine speed
    • PCM status