GM Service Manual Online
For 1990-2009 cars only

Caution: Keep hands, tools, and clothing away from the electric engine coolant fans in order to help prevent personal injury. These fans are electric and can turn on whether or not the engine is running. The fans can start automatically with the ignition in the ON position.

The electric radiator cooling fan is mounted behind the radiator and is activated by the engine coolant temperature (ECT) sensor. This sensor is mounted in the thermostat housing on both VIN 6 and VIN 9 applications and is calibrated to match the specifications of either the A or B type thermostat.