THE NEW PIPER AIRCRAFT, INC.
PA-32-301FT / 301XTC
MAINTENANCE MANUAL
PAGE 2
Jun 1/03
2C14
21-50-00
The air conditioning system in these airplanes uses HFC-134a. Refrigerant enters the compressor
as a vapor. The compressor pressurizes the heat laden vapor until the vapor temperature becomes
warmer than the outside air temperature. The compressor then pumps the vapor to the condenser
where the refrigerant is cooled and changes to liquid. The liquid now passes to the
receiver/dehydrator. The receiver/dehydrator filter removes moisture and ensures a steady flow of
liquid refrigerant (which is visible in the receiver/dehydrator’s sight glass) into the evaporator
through the expansion valve. The expansion valve is a temperature controlled metering valve which
regulates the flow of liquid refrigerant to evaporator. The evaporator enables the liquid refrigerant to
absorbs heat from the outside air passing over coils, converting it back to a vapor. From the
evaporator, heat laden refrigerant in a vapor state returns to compressor, and the cycle repeats.
B. Troubleshooting
Troubles peculiar to air conditioning system components are listed in Chart 1, with probable causes,
and suggested remedies. Correct trouble and check entire system for security and components
operation. The following definitions apply:
(1) High Side: Consists of all lines and components between the compressor outlet and the
expansion valve. It includes the condenser and receiver sight gauge.
(2) Low Side: Consists of all lines and components between the expansion valve and the
compressor inlet. It includes the evaporator.
(3) Service Ports: Located on evaporator unit, and are used for evacuating and charging the
system. The port in the short line between the receiver and the expansion valve is the high
side service port. The other port, located nearby, is the low side service port. The Schrader
valves used in these ports are of the quick-disconnect type. The service hose couplers used in
conjunction with this type of valve have a manually operated valve built in. After attachment,
this coupler valve must be manually turned clockwise (in), to depress the Schrader valve
spring and open it.
CAUTION: UNITED STATES ENVIRONMENTAL REGULATIONS REQUIRE USE OF A
COLLECTION SYSTEM WHEN EVACUATING REFRIGERANT FROM AIR
CONDITIONER.
NO
TE: Check all environmental regulations for your local area before servicing air conditioning
system.
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