General information
The air conditioning system consists of a condenser located in front of the radiator of the cooling system, an evaporator located next to the heat exchanger of the heater, a compressor driven by a drive belt, a receiver / dryer, as well as various pipes connecting the above components. A damper is installed at the inlet of the evaporator, which provides the pressure drop necessary for the operation of the system.
The fan delivers warm air from the passenger compartment to the evaporator (analog radiator), where heat from the air is transferred to the refrigerant. The refrigerant then evaporates and leaves the evaporator.
Diagram of the working circuit of the front automatic air conditioner
1 - Vacuum receiver; 35 - Divider; 36 - Vacuum valve assembly; 37 - Vacuum element of the servo actuator of the air duct damper of the left glass blowing nozzle; 38 - Vacuum element of the servo actuator of the air duct damper of the left glass blowing nozzle; 41 - Vacuum element of the servomotor of the deflecting damper of the air duct of the central nozzle; 44 - Vacuum element of the servo drive of the main air damper; 45 - Vacuum element of the servomotor of the mixing damper of the air duct of the left central nozzle; 46 - Vacuum element of the servomotor of the mixing damper of the air duct of the right central nozzle; 47 - Vacuum element of the servo actuator of the damper of the left foot air duct; 48 - Vacuum element of the servo actuator of the damper of the right foot air duct; 49 - Vacuum element of the servomotor of the damper for switching circulation modes; Y11 - Valve block bl - blue; dgn - dark green; drt - dark red; hbl - blue; ge - yellow; gr - grey; mgn - green; rt - red; orange - orange; sw - black; ws - white
Diagram of the operating circuit of the rear automatic air conditioner
1 - Vacuum receiver; 36 - Vacuum valve assembly; 50 - Vacuum element of the right rear foot well; 51 - Vacuum element of the left rear foot well; Y67 / 1 - Vacuum valve for the rear air duct damper servo; bl - blue; dgn - dark green; drt - dark red; hbl - blue; ge - yellow; gr - grey; mgn - green; rt - red; orange - orange; sw - black; ws - white
On models equipped with automatic air conditioning, all distribution dampers are vacuum operated. Vacuum from the receiver (30) and the vacuum valve assembly is fed into the valve block (Y11), which ensures its supply to the drive of the corresponding dampers (37 ÷ 49) in accordance with the settings selected from the A/C control panel (see also Comfort Chapters Manual).
Precautionary measures
Attention! The system is under pressure! Do not attempt to disconnect any pipes related to the air conditioning system without first removing the working fluid from it.
Removing fluid from the system is a rather complicated operation that must be performed at a service station.
The system contains refrigerant type R134a. Make sure the station has the equipment required for this type of refrigerant.
Wear safety goggles when disconnecting the system tubing.
If your vehicle has an air conditioning system, observe the following precautions when servicing any of its components:
- The R134a refrigerant currently in use is significantly less corrosive than the former R12 refrigerant. However, it is very hazardous to health. Avoid contact with eyes or skin - you may get burned. Although not toxic, its fumes can cause suffocation - do not remove it from the system while in an enclosed area. Its vapors are heavier than air, so do not stand under the vehicle when removing it from the system;
- Keep refrigerant vapors away from open flames. When it burns, poisonous gas is released. Gas mixed with air in a certain proportion can become explosive. Inhalation of vapors through a lit cigarette can lead to tragic consequences;
- Do not allow refrigerant to enter the atmosphere. Unlike R12, R134a type refrigerant does not cause ozone depletion, but leads to the appearance of a greenhouse effect in the atmosphere;
- The system uses seals made of a special material designed to work with a given type of refrigerant (for 134a - green). In order not to accidentally mix different types of refrigerants, certain types of adapters are used to charge a specific type of refrigerant;
- The system should be discharged at a Mercedes-Benz workshop;
- Before carrying out any work related to the heating of any vehicle components (welding, soldering, drying after painting), discharge the system. It is also necessary to discharge the system before servicing any of the air conditioning system components.