GM Service Manual Online
For 1990-2009 cars only

The fan shroud electrical fan motors drive the engine cooling fans. The fan shroud is located at the base of the radiator. The fan motors both have five blades that are each 312 mm (12.3 in) in diameter. The blades operate at two speeds, high and low.

The engine cooling fan relays provide the high current required for the motors, based on a ground signal received from the power control module (PCM).

The cooling fan relays are used to control the high current flow to power the cooling fan motors. Both fans operate together. When minimum cooling is required, the PCM energizes CoolFan1(#45) and both fans operate at low speed, since the fans are connected in series through CoolFan2 (#43) and CoolFan3 (#44). When maximum cooling is required, the PCM energizes all three cooling fan relays. The left fan is still powered through CoolFan1, but is now grounded through CoolFan3. The right fan is now powered directly through CoolFan2 and both fans operate at high speed.