RJ150-30 / Operations and Maintenance Manual
Mobile Aircraft Air Conditioner
Trailer Mounted, Cool Mode Only
______________________________________________________________________________
JANUARY 20, 2004
SECTION 2 - 2
PAGE 5
Fault & Condition
Probable Cause
Test, Check, Remedy
1. Expansion valve stuck in
"open" position (indicated by
abnormally cold suction line)
Ensure feeler bulb is tight on
suction line. Check hot gas
bypass regulator valve. Adjust or
replace valve. Refer to Section
2-4.
2. Low compressor oil level
Check compressor oil level sight
glass. Compressor must be
operating for approximately 10
minutes to get accurate level
reading. Service oil as required.
Noisy compressor
3. Incorrect phase shift (if
electrical repair has been made
to unit)
Check the compressor electrical
power 3-phase for proper phase
connections.
1. Flash gas in liquid refrigerant
line (indicated by a foamy or
bubbly sight glass)
Locate and repair leak in
refrigerant system. Recharge
refrigerant to proper levels.
2. Expansion valve stuck in
closed position; possible
obstruction, or broken capillary
tube
Replace valve and/or power
head assembly
3. Clogged filter-drier (housing
feels cool to the touch)
Replace filter-drier
Poor or insufficient cooling;
ambient air above 50
°
F (10
°
C)
4. Air side of evaporator coil is
dirty
Clean coil
1. Insufficient condenser airflow
(indicated by excessively warm
air leaving the condenser)
Check condenser fan operation.
Clean condenser coil inlet and
outlet if required.
2. Air or other non-condensable
gas in system
Evacuate system and recharge.
Install new filter-drier
3. High refrigerant charge
Purge or remove excess from
high pressure side of system
Head pressure too high
4. Faulty condenser motor (M3)
Check M3 for proper operation.
Replace as required.
Head pressure too low
Low refrigerant charge
Locate and repair leak in
refrigerant system. Recharge
refrigerant to proper levels.
1. Expansion valve stuck in
"open" position (indicated by
abnormally cold suction line)
Repair / replace valve as
required.
Suction pressure too high
2. Hot gas regulator valve set
too far "open"
Adjust valve setting. Refer to
Section 2-4. Repair / replace
valve as required
1. Ball valve closed
Check shutoff ball valve and
open if required.
Suction pressure too low
2.Hot gas regulator valve set too
low
Adjust regulator valve. Refer to
Section 2-4
