GM Service Manual Online
For 1990-2009 cars only

The cooling system has 2 plastic fans. Individual electric motors drive the fans, which are controlled electronically by the Powertrain Control Module (PCM). Engine coolant and the A/C high-pressure refrigerant temperature control a variable fan speed.

Both fans go on at a low speed when a calibrated engine coolant or an A/C high-pressure refrigerant temperature increases and reaches full power at a higher calibrated engine coolant or A/C high-pressure refrigerant temperature.

The fans eliminate unwanted on-off fan operation by using turn-off temperatures that are lower than turn-on temperatures. When the system demands more cooling, the left fan operates at high speed until the need is met.

Relays and switches operate the cooling fans.