Heater and air conditioner in the cabin (BMW 3 Series E46)

Cabin Air Conditioner Circuit Diagram

Heater. Models without air conditioning

Heater. Models with air conditioning

Air Conditioning Compressor Holder. Models 316i, 318i

Fresh air enters the cabin through the air collection box, the cabin ventilation air filter and the fan casing. The air passes through the heater box and is distributed through various flaps to individual nozzles. The air supply is determined by the number of revolutions of the fan electric motor.



Depending on the set temperature in the cabin, fresh air can be directed to the heat exchanger. The heat exchanger is located in the heating box and is heated by hot coolant. The air passing through the heat exchanger is heated as a result of washing the heat exchanger plates and then enters the cabin. The heating power of the heater is regulated by the coolant flow rate. This is done by an electromagnetic valve on the liquid pipeline.

Diesel engine due to its higher efficiency, it has a low thermal output. Therefore, a separate heater is required here, which additionally heats the coolant if necessary. The additional heater is heated by fuel from a separate fuel pump and is automatically connected if necessary.

Heating without air conditioning: The temperature in the cabin can be set by the regulator. The other two regulators set the speed of the four-stage heater fan and distribute the air through the nozzles.

Air conditioner: The interior temperature is set by a button on the control panel and is displayed on the digital display. Accordingly, the electronic control device of the air conditioner automatics regulates the opening of the heater valve depending on the interior temperature. The interior air temperature sensors are located in the control panel behind the air inlet grilles. Electronic regulation allows maintaining the interior air temperature constant, regardless of the vehicle speed and outside temperature.

When the air conditioner is turned on, the air is first cooled, dried and then, depending on the set temperature, heated again.



If fresh air intake is not permitted, for example due to poor outside air quality, the system can be switched to recirculation mode by pressing the appropriate button. In this case, the interior air is circulated in the passenger compartment.



When turned on "Automatischer Umluft Control" ("Automatic circulation control" - special equipment) the system switches on automatically to the circulation mode as soon as harmful components appear in the outside air, for example, soot from the combustion of diesel fuel. If the quality of the outside air is restored again, the system automatically switches to the consumption of outside air.

Air conditioner operation

The air conditioner works like a refrigerator: the compressor, driven by an electric motor, compresses the refrigerant in the gas phase, free of FCKW (R 134 a), and does not harm the environment. The refrigerant is heated and directed to the condenser. There it cools and liquefies. Through the expansion valve, the refrigerant expands and enters the evaporator, where it evaporates due to its low pressure. As a result of the expansion process, the air passing through the system of pipes and plates from the outside gives off heat.



In this way, the air is cooled and the moisture contained in it turns into condensation, which is discharged outside the car.

When the engine is running and the fan is on, cooled air can be supplied to the passenger compartment through various openings. The intensity of cooling depends on the set temperature and the number of revolutions of the fan motor.

The electronic control unit is built into the air conditioner control element.

Condensation forms in the air conditioner and is discharged outside the vehicle. This is a normal condition and does not indicate any malfunctions in the vehicle.

Air conditioning repair is not described here. This work should be performed in a specialized workshop.

Do not open the air conditioner cooling circuit, as liquid coming into contact with the skin may cause frostbite.

If the liquid accidentally gets on your skin, immediately wash the affected area with cold water for at least 15 minutes. The air conditioner fluid is colorless and odorless and is heavier than air. If the coolant leaks, there is a risk of poisoning in the lower part of the car (the presence of liquid is not felt).

[The original material is located on the website: www.bmwman.ru]