Automotive AC – Engine Fan and Condenser Fan

Vehicles that do not use a belt-driven engine cooling fan will use an electric fan to control engine temperature and to cool the condenser when the conditions require it. The engine/condenser fan is a vital part of the AC system when operating in high ambient temperatures as well as at low vehicle speeds. When the AC system is operating, the condenser is receiving hot, high-pressure gaseous refrigerant that must be cooled down while in the condenser. The airflow created by driving the vehicle at highway speeds is sufficient to allow this heat exchanger to work very well. When the vehicle is slowed down or stopped, the engine fan must provide airflow across the condenser.

The electric engine fan is typically controlled by a relay or a fan module. Both of these components are controlled by the engine control module that is constantly monitoring engine temperature as well as the AC pressures. When the AC high side pressure rises above a preset level, the engine control module signals to turn on the electric fan, which causes the condenser to be cooled and work more efficiently.

The main components in the circuit include the pulse width modulated blower motor, the blower motor control module, the HVAC control module, the HVAC control head, and the fuses. This system requires the use of advanced testing techniques and tools to diagnose and repair. The blower motor speed is controlled with a pulse width signal from the blower control module, which is very often combined with the blower motor and must be replaced as an

Many cars and trucks that use electric fan cooling will use a dual fan setup to add extra cooling capacity. These systems are engineered to operate one fan when the heat load is lower but can operate both fans when extra cooling capacity is

Electric cooling fans are very common on late-model cars and trucks because they can provide cooling for the radiator and condenser without robbing horsepower like belt-driven fans did. The fan assembly should be fastened in a secure method to the front part of the vehicle. The fan shrouds should be closely checked to ensure that they are installed

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