Radiator Cooling Fan Motor: Description and Operation

DESCRIPTION
The fan control system consists of:
1. Two, two-speed cooling fan motors attached to a fan shroud located behind the radiator.
2. A Powertrain Control Module (PCM).
3. A Constant Control Relay Module (CCRM). The CCRM is connected electrically to the:
a. The PCM, the A/C cycling switch, the A/C clutch coil circuit, and the cooling fan motors.
b. The cooling fan motors are wired to operate only when ignition switch is in the RUN position, thereby preventing radiator electric motor operation after the ignition switch is turned to the OFF position.
4. Related wiring.

OPERATION
1. Cooling fan motors will run at low speed if:
a. The engine temperature is higher than normal. Cooling fan motors start running at 102° C (216° F) and stops running at 100° C (212° F).
b. The A/C is on and the vehicle speed does not provide enough natural airflow. The cooling fan motors will stop running at speeds over 61 km/h (38 mph) if coolant temperature is below 100° C (212° F) and A/C head pressure is below 250 psi.

NOTE: The cooling fan motors will not cycle with the A/C clutch. The cooling fan motors will come on when the A/C switch is turned ON.

2. The cooling fan motors will run at high speed if:
a. The engine temperature is higher than desirable and cooling fan motors have been operating at a low speed. The cooling fan motors start running at high speed when the coolant temperature exceeds 109° C (228° F) and return to low speed when coolant temperature drops to 106° C (222° F).
b. A Wide-Open Throttle (WOT) A/C cutout is used during hard acceleration. A signal is sent to the powertrain control module which then signals the CCRM to cut off power to the A/C clutch field coil. This keeps the engine from being overloaded.

WARNING: Disconnect the cooling fan motors prior to performing any underhood service since the cooling fan motors could cycle if the ignition switch is left in the on position even though the engine is not running.