When the heater is switched to the warm air supply mode, the heater control valve in the engine compartment opens the supply of coolant to the heater radiator. Radiator (heat exchanger) is located in the heater housing and is heated by hot coolant. The outside air approaching it is heated by the hot fins of the heater radiator and then enters the car's interior. The electromagnetic heater control valve is controlled by a potentiometer, which is located behind the warm air supply regulator in the control unit. It can provide all positions - from fully open to fully closed. When the valve is closed, the coolant flows through the bypass channel back into the engine cooling system circuit.
A 4-stage heater fan serves to increase the efficiency of the heater. To ensure that the fan operates at different speeds, load resistors are installed. If one of the resistors fails, the engine does not operate at the appropriate speed.
By switching on the air circulation, the supply of outside air can be completely closed. In this case, only air from the car's interior will circulate in the passenger compartment using the fan. The air circulation mode flap is controlled by a push-button switch with a control lamp and a drive motor.
Air filter for supplied air (for the Ford KA model: additional equipment) traps contaminants in incoming air such as pollen, dust or other microparticles.
The article is based on website data: MAZBOOK.ru
An air conditioning system is installed as additional equipment. Repair of the air conditioning system is not described.
Precautions: Work on the air conditioning system should be carried out in a workshop. Under no circumstances should the refrigerant circuit be opened, as the refrigerant may cause frostbite if it comes into contact with the skin.