The A/C compressor is the central element of a vehicle air conditioning system and is driven by the engine. It compresses the refrigerant in the refrigerant circuit of the air conditioner.
Today's chemical refrigerants for motor vehicle air conditioning systems belong to the group of partly fluorinated hydrocarbons (R134a) or (partially) halogenated alkanes (HFO-1234yf) and contribute to the greenhouse effect. When replacing the compressor and performing any other work on the air conditioning system care must therefore be taken to ensure that refrigerant is not allowed to escape into the environment. The refrigerant and the refrigerant oil removed must also be disposed of in the proper manner.
The design of a refrigerant compressor means that it is only able to convey gases and vapours. As liquids cannot be compressed, they must never be allowed to enter the compression chamber. If this were to happen, it would have the following consequences:
This in turn would cause piston damage.
Damage to the A/C compressor affects the entire air conditioning system. If damage occurs, the first step is to establish the cause of compressor failure. It is advisable to start by checking whether the compressor shaft is turning or whether there is a problem with the magnetic clutch or overload safeguard. The following are also possible causes of compressor damage:
The compressor draws in the refrigerant gas from the evaporator. This in turn leads to a drop in pressure in the evaporator. The resultant lower pressure makes the refrigerant evaporate at low temperatures. The cold vapour is then compressed by the A/C compressor. The refrigerant gas warmed in the course of compression is conveyed via pipes to the condenser, where it liquefies again, giving off heat in the process. It is then routed to the area to be cooled. Here, the refrigerant absorbs the heat of the air flowing into the passenger compartment and turns back into gas at the evaporator. It is then drawn in again by the compressor, where it is compressed.
The compressor is attached to the engine block and is driven by a pulley and a V-belt. When the air conditioning system is switched on, the belt drive is set in motion by a magnetic clutch. The compressors used in modern vehicle air conditioning systems are of compact, lightweight design. This was a prerequisite for the series installation of air conditioners in compact class cars.
The following components make up an A/C compressor:
A distinction is made between the following types:
The most commonly used type is the swash plate compressor.
Regular expert servicing of the air conditioning system can help to prevent compressor damage. Should it nevertheless become necessary to replace the compressor, certain other steps also have to be taken. The following points must be heeded: