Subaru 2002 Impreza Service Manual page 378

AIR CONDITIONER
HVAC System (Heater, Ventilator and N C )
2. EXPANSION VALVE
The expansion valve regulates the flow of refrigerant such that heat exchange takes place optimal-
The expansion valve performs two functions; it sprays the high-pressure refrigerant from the con-
denser using a throttle valve, and it regulates the amount of the spray by changing opening of the
throttle valve.
The expansion valve consists of such main components as a heat sensing cylinder, diaphragm,
ball valve, spring, and adjusting screw.
ly.
(1)
Ball valve
(2) Shaft
(3) Heat sensing part
(4)
Diaphragm
NF0175
Flow of refrigerant
From evaporator (low-pressure side)
To compressor
From condenser
To evaporator (high-pressure side)
The heat (temperature) sensing cylinder is held in contact with the evaporator outlet pipe so that
a pressure corresponding to the sensed temperature may be applied to the chamber above the
diaphragm. There is a pressure equalizing hole which communicates with the chamber below the
diaphragm to transmit changes in the refrigerant pressure to the chamber. The ball valve is linked
with the diaphragm and moves according to changes in the balance between the force applied
to the diaphragm and the tension of the spring.
AC-14