System Outline

Fan Motor Operation 

When the ignition SW is turned on, current flows through the ECU-IG fuse to the FAN NO. 1 relay (Coil side), FAN NO. 2 relay (Coil side) and FAN NO. 3 relay (Coil side).

1. Low Speed Operation 

   When only the A/C system is activated, the A/C condenser fan motor and the radiator fan motor rotate at low speed.

   When the A/C system is activated, current from the ECU-IG fuse flows to the FAN NO. 3 relay (Coil side) to TERMINAL 2 of the diode (Fan), out TERMINAL 3 to TERMINAL (B) 2 of the engine control module causing the FAN NO. 3 relay to turn on. As a result, the current flows through the CDS fuse to TERMINAL 5 of the FAN NO. 3 relay, out TERMINAL 3 to TERMINAL 2 of the A/C condenser fan motor, then out TERMINAL 1 to TERMINAL 3 of the FAN NO. 2 relay, and out TERMINAL 4 to TERMINAL 2 of the radiator fan motor then finally out TERMINAL 1 to GROUND. As the motors are in series, they only rotate at low speed.

2. High Speed Operation 

   When the pressure SW is turned on and/or the engine control module activated, the A/C condenser fan motor and the radiator fan motor rotate at high speed.

   When the pressure SW is turned on, current flows through the ECU-IG fuse to the FAN NO. 1 and NO. 2 relay (Coil side), out TERMINAL 3 of the pressure SW, the out TERMINAL 2 to GROUND, and the current which flows through the ECU-IG fuse goes to the FAN NO. 3 relay (Coil side), then to TERMINAL 2 of the diode (Fan), and out TERMINAL 1 to TERMINAL 3 of the pressure SW, then from TERMINAL 2 to GROUND. As a result, the FAN NO. 1, NO. 2. and NO. 3 relays are turned on. At the same time, current from the RDI fuse flows to the FAN NO. 1 relay (Point side), then to TERMINAL 2 of the radiator fan motor, and out TERMINAL 1 to GROUND, and current from the CDS fuse flows to the FAN NO. 3 relay (Point side) to TERMINAL 2 of the A/C condenser fan motor, then out TERMINAL 1 to TERMINAL 3 of the FAN NO. 2 relay, and out to TERMINAL 5 to GROUND.

   As the current is flowing in parallel to the motors, they rotate at high speed. When the engine control module is activated, the current from the ECU-IG fuse flows to the FAN NO. 1 and NO. 2 relays (Coil side), then to TERMINAL (E) 14 of the engine control module, and the current from the ECU-IG fuse flows to the FAN NO. 3 relay (Coil side) to TERMINAL 2 of the diode (Fan), and out TERMINAL 1 to TERMINAL (E) 14 of the engine control module. As a result, the FAN NO. 1, NO. 2 and NO. 3 relays are turned on. At the same time, current from the RDI fuse flows to FAN NO. 1 relay (Point side) to TERMINAL 2 of the radiator fan motor, and out TERMINAL 1 to GROUND, and current from the CDS fuse flows to the FAN NO. 3 relay (Point side) to TERMINAL 2 of the A/C condenser fan motor, out TERMINAL 1 to TERMINAL 3 of the FAN NO. 2 relay, then out TERMINAL 5 to GROUND.

   As the current is flowing to the motors in parallel, they rotate at high speed.