For 1990-2009 cars

The condenser fan is crucial to the proper operation of the air conditioning system. The fan ensures a sufficient amount of airflow across the condenser throughout the vehicle's operating range. The fan should be checked during all air-conditioning diagnosis procedures. Special attention should be given to the fan whenever excessive high-side pressure is encountered.

When the A/C is off and the engine coolant temperature is below 83°C (181°F), neither the main, nor the auxiliary fan motor runs. When the A/C is off and the engine coolant temperature reaches 93°C (199°F), each fan motor runs at full speed.

When the engine coolant temperature is below 83°C (181°F) and the A/C is requested, both fan motors are in series and run at half speed.

When the A/C is on and the engine coolant temperature reaches 93°C (199°F) the fans run in parallel at full speed.

Both fans will cycle on and off at full speed as the engine coolant temperature increases and decreases. Since the variable displacement compressor runs constantly, the fans will not cycle on and off with A/C compressor operation.

When terminal 8 of the data link connector (underhood) is grounded, either for engine diagnostic purposes or accidently, the A/C System will be inoperative below 1200 RPM.