Mercedes C-Class

W203 since 2000 of release

Repair and operation of the car



Mercedes-Benz
+ Mercedes-Benz cars of class C (W-203)
+ Operation manual
+ Routine maintenance
+ Engine
- Cooling system and heating
   + Cooling system
   - Systems of ventilation, heating and air conditioning
      Removal and installation of ventilating deflectors
      Removal and installation of electric motors of the drive of gates
      Removal and installation of the control unit of a heater and conditioner
      Removal and installation of an electric motor of the fan of a heater or conditioner
      Removal and installation of the electronic regulator of the fan of a heater or conditioner
      Removal and installation of sensors of the conditioner
+ Power supply system and release
+ Engine electric equipment
+ Manual transmission
+ Automatic transmission
+ Coupling and power shafts
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment







Systems of ventilation, heating and air conditioning

General information and security measures

Distribution of air streams


Scheme of a contour of the conditioner of air

1 — the Fan
2 — the Evaporator
3 — the Broad valve
4 — the Tank
5 — the condenser Fan
6 — the Condenser
7 — the Compressor
and — External air for cooling of the condenser
b — the Warm air which is taken away outside
with — not cooled air going via the fan
d — the Cooled air going to salon
And — High pressure, gaseous
In — High pressure, liquid
With — Low pressure, liquid
D — Low pressure, gaseous

Additional electric heater. Diesel engine

1 — the electric heater Block
2 — Sealing laying
3 — the Heating element

Management of an air stream and filters of the air conditioning system


The fresh air given by system of ventilation to interior of the car via filters of rough and thin cleaning can be warmed up or cooled depending on the choice of the driver and passengers. The heater, on models without conditioner, or the conditioner of air settles down in salon, in the case under the dashboard. All stream of the air given to salon goes for heating or cooling through the same casing. Temperature and speed of a stream of air is regulated by means of the governing bodies located on the control panel.

Regulation of speed of rotation of the fan is carried out by the electronic device, Heat generated during the operation of the engine is transferred by cooling liquid to the heater radiator located in salon. The brought air stream from system of ventilation passes through a radiator and heats up heat of the cooling liquid of the engine proceeding in a radiator. Extent of heating is regulated by means of mixing in a certain ratio of cold and hot air by means of the mixing gate with the servo-driver.

The used air is removed from salon through air vents with backpressure valves.

Increase in a consumption of air via the heat exchanger provides the fan of fresh air.

If it is necessary to turn off supply of fresh air, for example, at a bad smell, the system switches in the circulation mode at which external air does not come to salon.

Switching of system in the mode of circulation is confirmed by fire of a control lamp.

If on the car the diesel engine is installed, then there is an additional electric heater which is built in a contour of cooling of the engine, and included at a low temperature of external air. If external temperature falls below +8 °C and at the same time temperature of cooling liquid makes less than 70 °C, the additional heater joins, depending on position of the regulator of temperature in salon, and automatically lifts temperature of cooling liquid that provides heating of interior of the car.

The additional heater is located on the block of cylinders, over a starter at the left, looking in the direction forward.

Works with air conditioning system have to be performed by experts.

The conditioner of air is capable both to warm up and cool, and to drain the air coming to salon. During wet weather, the arriving fresh air previously it is cooled then again heats up to the set temperature. At the same time there is a condensation of excessive moisture of air, i.e. its drainage. Thus fogging of glasses is eliminated.

The drainage mode, depending on humidity of air, has three steps of management.

The conditioner consists of a heater and the refrigerator. The conditioner refrigerator - from the compressor, the condenser, a throttle, the evaporator, the container with coolant and pipelines. In system coolant (R134a type) which, depending on temperature and pressure, can be in liquid or gaseous state circulates.

The compressor of the conditioner is given to rotation from a bent shaft of the engine by means of a ridge belt. He creates pressure to 30 atm. in an installation cooling contour owing to what the coolant representing gas heats up. In the condenser coolant is cooled with the external air (which is not coming to salon). Thereof the warmed coolant is condensed, turning into liquid. Having big pressure, it is passed through a throttle therefore its pressure falls. After that coolant evaporates, at the same time strongly being cooled. In the evaporator coolant selects heat from the air blown through it. Air is cooled. The cooled air comes to interior of the car. As a result of heating in the evaporator coolant turns into gas and under low pressure comes to the compressor then process of circulation repeats.

To order the car can be equipped with the automatic conditioner of air (climatic installation). At the same time two options of the installations differing in touch management and automatic equipment of comfort are possible.

Security measures at service of the air conditioner

Air conditioning system has to be served by exclusively prepared technicians trained in safe working methods with use of the appropriate equipment with observance of rules of depressurization, acquainted with methods of collecting and order of storage of automobile coolant.

· Do not allow contact of coolant with skin.
· During the work near air conditioning system put on goggles.
· At hit of coolant on skin or eyes do not pound the struck place. Immediately wash out cold water within not less than 15 minutes. Immediately see a doctor or in medical institution. Self-treatment is not allowed.
· Coolant is stored in a new cylinder under pressure. You store a cylinder at a temperature not above 50 °C. Take the measures excluding falling of a cylinder about heights or other situations which can lead to its damage.
· Works should be carried out in well aired room. Coolant quickly evaporates, has no smell. Its accumulation leads to reduction of access of oxygen and difficulty of breath.
· Gaseous coolant is heavier than air and rather quickly has to gather below, for example, under the car.
· At combustion of coolant poisonous gas is formed. You store coolant far from open sources of fire. You do not smoke. When using an ardent techeiskatel avoid smoke inhalation.
· When carrying out welding works near air conditioning system to influence of high temperature or an open flame. The overheat can lead to increase in pressure in system and to ignition.
· Cleaning of the condenser or evaporator by means of water vapor is not allowed. It is necessary to use only cold water or compressed air.
Обзор BQ BQS-5520