Piper PA-44-180 SEMINOLE Maintenance Manual page 160

CHART 2104. TROUBLESHOOTING (AIR CONDITIONER)
Gauge Indication
High discharge pressure
Low discharge pressure.
Low suction pressure.
(Accompanied by icing
evaporator.)
Low suction pressure.(Evaporator
not cold enough) suction
gauge may read a vacuum
indicating evaporator lacks
refrigerant.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
Probable Causes
Overcharge of refrigerant
Air in system
Overheated condenser due to
blocking air passage.
Flooded evaporator indicated
by heavy frosting on suction line
and compressor suction service
valve.
Restriction in liquid line from
condenser.
Undercharge of refrigerant.
Sight glass shows bubbles or
foam.
Damaged compressor valves or
dirt under valves.
Damaged compressor. Worn or
broken piston or piston rings.
Low air supply through
evaporator.
Very dirty evaporator fins and
coils.
Undercharge of refrigerant.
Moisture freezing in expansion
valve. Valve will show frost.
Expansion valve inlet screen
clogged. Inoperative expansion
valve. Valve stuck closed or
capillary bulb has lost its charge.
Restriction anywhere in liquid
line. Restriction will show frost.
1G16
Remedy
Purge excess refrigerant
Check for leaks. Bleed charge
from system. Evacuate and
recharge system.
Clean bugs and dirt from
condenser fins. Straighten fins if
bent.
Check that capillary bulb is
securely clamped to suction line.
If capillary bulb OK replace
expansion valve.
Check for kinked hoses and
stopped up filter.
Add refrigerant until bubbles
disappear. Check system leaks.
Replace compressor.
Replace compressor.
Repair blower or blower motor.
Clean stoppage in air ducts.
Clean and flush with water.
Add refrigerant. Install new
dryer. Evacuate and recharge.
Remove screen. Clean with
solvent and replace. Warm
capillary by holding in hand. If
suction pressure does not
change, replace expansion valve.
Locate restriction and repair.
Page 21-49
Revised: May 15, 1989
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