Radiator Cooling Fan Motor: Description and Operation
Without A/CRadiator fan operation is controlled by the radiator fan control module. The control module can turn on the fan motor anytime during the first 15 minutes after the ignition switch is turned off (0).
The control module applies voltage to the radiator fan relay coil. When engine coolant temperature reaches 93°C (199°F), engine coolant temperature (ECT) switch A closes, and energizes the relay coil. Voltage is then applied through fuse 47 to the relay, and the radiator fan motor, and because the motor is grounded at G201, the radiator fan starts running.
When the ignition switch is turned off (0), the radiator fan will stay on until engine coolant temperature (ECT) switch B opens (below 105°C, 221°F), or the control module opens the circuit (about 15 minutes).
With A/C
Radiator fan and condenser fan operation is controlled by the radiator fan control module. The control module can turn on the radiator fan motor anytime during the first 15 minutes after the ignition switch is turned off (0).
The control module applies voltage to the condenser fan relay and radiator fan relay coils. When engine coolant temperature reaches 93°C (199°F) (S, Si, SR) or 95°C (203°F) (VTEC, SR-V) engine coolant temperature (ECT) switch A closes, and energizes both relays.
Voltage is then applied through fuse 47 to the radiator fan relay and the radiator fan motor, and, because the motor is grounded at G201, the radiator fan starts running.
Voltage is also applied through fuse 45 to the condenser fan relay and the condenser fan motor, and, because the motor is grounded at G381 (S) or G301 (Si, SR, VTEC, SR-V) the condenser fan also starts running.
Both fans will run when the control module receives an "A/C request" signal from the BLU/RED wire when you turn on the A/C switch in the heater control panel.
When you turn the ignition switch off (0), the condenser fan will stop, but the radiator fan will remain on until engine coolant temperature (ECT) switch B opens (below 105°C, 221°F), or the control module opens the circuit (about 15 minutes).