Cabin Air Conditioner Circuit Diagram
1 - fan
2 - evaporator
3 - throttle
4 - low pressure service connection
5 - high pressure service connection
6 - dryer
7 - capacitor
8 - compressor:
- a - outside air for cooling the condenser
- b - warm air, discharged to the external environment
- c - uncooled air passing through the heater fan
- d - cooled air entering the cabin
A - high blood pressure (refrigerant in gaseous form)
B - high pressure (liquid refrigerant)
C - low pressure (liquid refrigerant)
D - low pressure (refrigerant in gaseous form)
Heater. Models without air conditioning
1 - fan
2 - clamp
3 - additional resistors. For individual fan stages
4 - drive block right
5 - microswitch
6 - gear for adjusting dampers
7 - heating box
8 - sealing frame
9 - sealing gasket
10 - fan cover
11 - front control panel
12 - switch. For heated rear window
13 - fan switch
14 - thrust. To adjust the temperature
15 - bracket
16 - roller. Air damper drives
17 - casing of the control unit
18 - screw
19 - handle
Heater. Models with air conditioning
1 - fan
2 - bracket
3 - fan controller
4 - temperature sensor
5 - ventilation damper drive
6 - heater / air conditioner box
7 - ventilation damper
8 - sealing gasket
9 - fan cover
10 - sealing frame
11 - screw, M4 x 14
12 - side cover of the heater box
13 - drainage hose. For air conditioner compressor
14 - additional heater. Additional diesel engine heater
15 - holder
16 - console
17 - screw M8 x 20, 24 Nm
18 - nut
19 - bar
20 - console
Air conditioner compressor holder. Models 316i, 318i
1 - compressor
2 - holder
3 - bolt, M8 x 55
4 - bolt, M8 x 100
5 - tensioner
6 - Torx screw, M8 x 55
7 - V-belt
Fresh air enters the passenger compartment through the air box, passenger compartment air filter and fan shroud. 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 motor.
Depending on the set interior temperature, 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 passenger compartment. The heat output of the heater is controlled by the flow rate of the coolant. This is done by a solenoid valve on the liquid line.
diesel engine due to the higher efficiency, it has an insignificant thermal performance. Therefore, it requires the installation of a separate heater, which, if necessary, additionally heats the coolant. The additional heater is heated by fuel from a separate fuel pump and is automatically switched on 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 to the nozzles.
Air conditioner: The temperature in the cabin is set with a button on the control panel and displayed on a digital display. In accordance with this, the electronic control unit for the automatic air conditioner regulates the opening of the heater tap depending on the temperature in the passenger compartment. The interior air temperature sensors are located in the control panel behind the air intake grilles. Electronic control keeps the interior temperature constant, regardless of vehicle speed and outside temperature.
When the air conditioner is switched on, the air is first cooled, dried and then reheated depending on the set temperature.
If the intake of fresh air is not allowed, for example if the outside air quality is poor, the system can be switched to circulation mode by pressing the corresponding button. At the same time, internal air circulates in the cabin.
When turned on "Automatischer Umluft Control" ("Automatic circulation control" - special equipment) the system switches itself into circulation mode as soon as harmful components appear in the outside air, for example, soot from the combustion of diesel fuel. If the outdoor air quality is restored again, the system automatically switches to outdoor air consumption.
Air conditioner operation
The air conditioner works like a refrigerator: a compressor driven by an electric motor compresses the refrigerant in the gas phase, free from FCKW (R 134 a), and not harmful to the environment. The refrigerant is then heated and sent to the condenser. There it cools and liquefies. Through the expansion valve, the refrigerant expands and enters the evaporator, where, due to its low pressure, it evaporates. 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 it contains turns into condensate, which is discharged outside the vehicle.
When the engine is running and the fan is on, cool air can be drawn into the passenger compartment through various openings. The amount of cooling depends on the set temperature and the speed 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 normal and does not indicate any problems with the vehicle.
Air conditioner repair is not described here. These works must be carried out in a specialized workshop.
Do not open the cooling circuit of the air conditioner, as contact with the skin may cause frostbite.
In case of accidental contact of liquid with the skin, immediately rinse the affected area with cold water for at least 15 minutes. The air conditioner fluid is colorless and odorless and heavier than air. If coolant leaks, there is a risk of poisoning in the underside of the vehicle (the presence of liquid is not felt).