It is necessary for a large volume of air to pass through the radiator for it to release the heat. Ordinary driving provides an adequate air flow for cooling, however when the vehicle is stopped or is driving at low speeds the volume of air becomes inadequate. Therefore the engine is equipped with a cooling fan to force airflow to the radiator. The electric fan system senses the coolant temperature, and supplies an adequate amount of air only when the temperature is high. At normal temperature, the fan is stopped, which allows the engine to warm up and decreases fuel consumption and noise. Electric fan rotation speed can be switched between three stages or to stageless so that cooling performance can be adjusted to synchronize with the coolant temperature and AC operation.
(1) Low coolant temperature:
The coolant temperature switch goes on and the fan relay is grounded. The magnetic force of the relay coil keeps the points off, stopping electrical current from reaching the fan motor.
(2) High coolant temperature:
The coolant switch goes off and the fan relay circuit is interrupted. Then, the points go on, supplying current to the fan motor and causing the fan to revolve at high speed. HINT:
Recently, there are some models where the on/off points operation of the coolant temperature switch and the fan relay are reversed.
Always be sure that the ignition switch is turned off when working near the engine cooling fan or radiator grille. The electrical cooling fan is temperature controlled, so if the ignition switch is turned on, there is the danger of the fan automatically starting to operate when the coolant temperature rises.