Komatsu PC88MR-10 Shop Manual page 1337

a Do not try to drive a servomotor by supplying power directly between servomotor terminals (6) and (7)
during inspection.
Expansion valve
(ALL-K548-041-K-00-A)
A: When evaporator outlet temperature is high
B: When evaporator outlet temperature is low
C: From capacitor (high-pressure refrigerant)
D: To compressor (low-pressure refrigerant)
1. Expansion valve
1a. Needle valve
1a-1. Diaphragm
1a-2. Thermoprobe
1b. Spring
2. Refrigerant gas
3. Evaporator
Structure
Box-type expansion valve (1) consists of needle valve (1a), spring (1b), etc.
Refrigerant gas (2) is sealed in the diaphragm chamber (hatched area) outside diaphragm (1a-1) of
needle valve (1a).
Function
(ALL-K548-042-K-00-A)
The expansion valve (1) converts high-pressure and high-temperature liquid refrigerant from the receiver
drier to low-pressure, low-temperature misty refrigerant through the throttle action.
It controls the flow rate of refrigerant by changing the level of throttling depending on the temperature in
the cab.
The temperature of the air blown out of the air vent is adjusted depending on the flow rate of refrigerant
circulating in the evaporator (3).
PC88MR-10
80 Appendix
Air conditioner unit
80-13