Refrigerant Circuit

Switching on the air conditioner activates electromagnetic coupling (1) of compressor (2). The Compressor (2) is now driven by the running engine.
Compressor (2) increases the pressure of gaseous refrigerant, which automatically causes the refrigerant temperature to also rise.
The refrigerant puts off heat in condenser (3), through which it is condensed (turns into a liquid).
The receiver/drier (4) removes residual water from the refrigerant and absorbs it.
Safety switches (5 and 6) stop the compressor when pressure is too high or too low. In this manner damage is prevented in the air conditioning system.
Expansion valve (7) meters the amount of refrigerant which is injected into evaporator (8). The amount of refrigerant will depend on the temperature and pressure of refrigerant at outlet of the evaporator.
The liquid regrigerant expands in evaporator (8) and is turned into gas. This change in state produces strong cooling off of the refrigerant and evaporator. The fresh air (or bypass circulation air) is cooled as it passes through the evaporator.
Freezing prevention switch (9) switches the compressor to prevent the formation of ice on the evaporator. Ice formation would reduce the cross section opening size and impair cooling efficiency.
Moisture in the fresh air (or bypass circulation air) condenses on the evaporator and is discharged outside of car via lines on the transmission tunnel. This water is normal and not a sign of leakage.