Cooling System: Description and Operation
FansHow the Circuit Works
Battery voltage is provided at all times to the radiator fan relay contacts through fuse 11 (in the under-hood fuse/relay box) and to the A/C condenser fan relay contacts through fuse 9 (in the under-hood fuse/relay box). With the ignition switch in ON (II), battery voltage is supplied to the A/C condenser fan relay coil through fuse 30 (in the under-dash fuse/relay box). The PCM controls power to the radiator fan relay coil. The PCM uses input from the ECT sensors and the A/C pressure sensor to control the fans.
In normal operating coolant temperature conditions, the PCM grounds the A/C condenser fan relay coil. Battery voltage is provided to the A/C condenser fan motor and the radiator fan motor in series through fuse 9 (in the under-hood fuse/relay box).
In extremely high coolant temperature conditions, the PCM grounds the A/C condenser fan relay coil and the radiator fan relay coil. Battery voltage is provided to the A/C condenser fan motor through fuse 9 (in the under-hood fuse/relay box) and to the radiator fan motor through fuse 11 (in the under-hood fuse/relay box).
In both cases, the fans will run until ground is removed from the relay coil(s).