Subaru LEGACY 2002 Quick Reference Index page 491

4. CHECK VALVE
A check valve consisting of a spherical plate and spring is provided at the suction port of the rear
head. Immediately after the compressor has stopped, there is large difference between the high-
and low-pressures. This would cause reverse rotation of the compressor and consequent reverse
flow of refrigerant to the evaporator if no check valve is provided. Immediately after the compressor
has stopped, the high-pressure refrigerant forces the check valve plate upward and closes the
suction port to prevent flow of refrigerant from the high-pressure side to the low-pressure side.
(1) Refrigerant suction port
(2) Plate
COMPRESSOR
(3) Spring
(4) Check valve
AC-19
HVAC System (Heater, Ventilator and A/C)
(5) Refrigerant
B4H0751A