Subaru LEGACY 2002 Quick Reference Index page 496

COMPRESSOR
HVAC System (Heater, Ventilator and A/C)
2. FUNCTION
1) Start of suction — End of suction:
As the compressor rotates, the refrigerant gas from the evaporator moves through the suction
hose into the internal low-pressure chamber. Through the suction port provided in the front cylin-
der head, the refrigerant gas then enters the cylinder chamber (1).
2) Start of compression:
Further rotation of the rotor gradually reduces the volume of the cylinder chamber (1). The refrig-
erant gas in the cylinder chamber is therefore compressed and its pressure increases.
Air tightness between the cylinder chamber surfaces and the ends of the vanes is maintained by
a film of the oil which simultaneously lubricates the cylinder and vanes.
3) Compression — Start of discharge:
The rotor further rotates and the volume of the cylinder chamber (1) further decreases, confining
the refrigerant gas in a smaller space. The pressure of the refrigerant gas in the cylinder chamber
further increases.
When this pressure becomes higher than the pressure of the high-pressure chamber in the oil
separator case, the high pressure refrigerant gas forces the discharge valve to open and enters
the high-pressure chamber. The refrigerant is then routed to the condenser.
The pressure of the cylinder chamber (1) may become lower than the pressure of the high-pres-
sure chamber. If this happens, the discharge valve is forced to close by the pressure of the high-
pressure chamber, so counterflow of the refrigerant gas from the high-pressure chamber into the
cylinder chamber is prevented.
4) End of discharge:
The cylinder chamber (1) has completed compression and discharge of the refrigerant gas. It is
ready for starting the above-mentioned cycle again.
The other cylinder chambers (2), (3) and (4) perform the pumping function in exactly the same way
as the cylinder chamber (1).
B4H0652B
AC-24