Cooling System Description and Operation: LS1

The PCM commands low speed fans on under the following conditions:

• Engine coolant temperature exceeds approximately 108°C (226°F).
• When A/C is requested and the ambient temperature is greater than 10°C (50°F).
• A/C refrigerant pressure exceeds 1482 kPa (215 psi).
• After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.

The PCM commands High Speed Fans on under the following conditions:

• Engine coolant temperature reaches 112°C (234°F).
• A/C refrigerant pressure exceeds 1710 kPa (248 psi).
• When certain DTCs set.