3
-
Outlet line - additional evaporator (if present)
8
-
Inlet line - additional evaporator (if present)
10
-
High pressure (liquid and warm)
11
-
Low pressure (liquid and cool)
12
-
Low pressure (gaseous and cold)
13
-
High pressure (gaseous and hot)
The engine driven refrigerant compressor (2) sucks in gaseous refrigerant from the suction accumulator and compresses it. The temperature of the refrigerant rises to a value between 70 °C and 110 °C. It passes to the condenser (1) under high pressure.
At this point heat is drawn from the refrigerant by the air being forced past the cooling fins. Because of this heat loss, the refrigerant liquefies and leaves the condenser.
A fixed orifice tube (7), which separates the refrigerant at high pressure from that at low pressure, is located between the condenser and the evaporator (6). This fixed orifice tube slows down the flow of the refrigerant from the compressor, so that pressure builds up in the condenser.
After passing through the fixed orifice tube the liquid refrigerant expands in the circuit to the evaporator, where it becomes gaseous. Thereby, heat is removed from the air before it enters the passenger compartment. The air cools down, and excess moisture contained in it is condensed and is drained off. The refrigerant coming from the evaporator flows into the refrigerant accumulator and is again sucked in by the refrigerant compressor.
The system is protected by a high-pressure switch, in order to prevent damage by excessive pressure (e.g. because of overfilling with refrigerant). If the pressure exceeds the maximum permitted, the high-pressure switch turns off the refrigerant compressor.
The compressor on-off cycle is controlled by the low-pressure switch depending on the pressure in the refrigerant accumulator. The low-pressure switch turns the refrigerant compressor off permanently if the pressure falls below a permitted value (e.g. if there is a leak).
Overview - air conditioning system
