The compressor is driven by an engine driven pulley system. At the front of the compressor is a magnetic clutch which when given power engages the compressor. The compressor draws in refrigerant vapour from the suction side which is the outlet of the accumulator (fixed orifice valve system) or the outlet of the evaporator (expansion valve system). Because the refrigerant that left the evaporator/accumulator is a vapour it can no longer absorb heat energy and act as a cooler.
During the compression of the refrigerant inside the compressor the pressure and temperature rapidly increase.An ideal system will increase the pressure from 200 to 2250 kPa (29 to 326 psi). The temperature increase can be as much as 0°C–110°C.When the air-conditioning system is running the suction pressure is between 120 and 300 kPa (17.5 and 43.5 psi), when the system is under high load the pressure and temperature of the refrigerant can reach as high as 2800 kPa (406 psi) and 125°C.
The compressor can only compress refrigerant vapour. Any liquid or dirt allowed to enter the compressor will cause damage.
The boiling point of refrigerant at 326 psi is 57°C so the refrigerant will remain in a gaseous state until the refrigerant gives off enough heat to drop below 57°C.To do this the refrigerant flows from the outlet of the compressor to the condenser.