SECTION 22: HEATING AND AIR CONDITIONING
32
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Final Version – Rev.2 April 2016)
head pressure, insufficient liquid subcooling or
some form of restriction in the liquid line.
Moisture is one of the main causes of chemical
instability or contamination in air conditioning
systems. If moisture is present, it can corrode
the valves, condenser and evaporator coils,
compressor and other components causing a
malfunction and eventual failure of the system.
Uncontrolled moisture in the system can result in
very expensive multiple component
replacements if not corrected at an early stage.
The moisture indicator permits an early
detection of moisture in the system and when
corrected by a desiccant charge, system
contamination is greatly minimized.
CLEAR
Normal, system OK
Temporary condition, normal when A/C
system is turned on. Wait a few minutes
for the system to stabilize.
BUBBLES, FOAMY
Low refrigerant level
Excessive pressure drop in filter-dryer
Restricted filter-dryer
MILKY, CLOUDED
Contaminated system
OIL STREAKS
Oil contamination
FIGURE 38: CONDITIONS THAT MAY BE OBSERVED IN
THE MOISTURE INDICATOR SIGHT GLASS
7.8
SHUT-OFF VALVE WITH SERVICE
PORT
This shut-off valve (FIGURE 39) is located in the
condenser compartment. It is used to isolate one
section of the refrigerant circuit. The service port
is equipped with a Schrader valve.
FIGURE 39: REFRIGERANT CIRCUIT SHUT-OFF VALVE
FIGURE 40: REFRIGERANT CIRCUIT SHUT-OFF VALVE
7.9 LIQUID REFRIGERANT SOLENOID VALVE
The flow of liquid refrigerant to the driver’s unit
evaporator, passengers’ unit evaporator (main
evaporator) and parcel racks evaporator is
controlled by one NC (normally closed) solenoid
valve on each circuit, for a total of three solenoid
valves.
The driver’s unit solenoid valve is located on the
ceiling of the spare wheel compartment (
FIGURE
41
) and is accessible through the reclining
bumper.
Two identical NC (normally closed) refrigerant
solenoid valves are found in the condenser
compartment (FIGURE 42). One is used to
control flow of refrigerant to the parcel racks
evaporator while the other is used to control flow
to the main evaporator.
FIGURE 41: DRIVER'S UNIT LIQUID SOLENOID VALVE
