Piper Aircraft Corporation Malibu Mirage PA-46-350P, Airplane Maintenance Manual

Page: 319 / 1956

PAGE 1
Feb 28/07 2D17
21-50-00
PIPER AIRCRAFT, INC.
PA-46-350P, MALIBU MIRAGE
MAINTENANCE MANUAL
COOLING
1. General
WARNING: FAILURE TO CONSULT APPLICABLE VENDOR PUBLICATION(S), WHEN SERVICING
OR INSPECTING VENDOR EQUIPMENT INSTALLED IN PIPER AIRCRAFT, MAY
RENDER THE AIRCRAFT UNAIRWORTHY. (SEE INTRODUCTION - SUPPLEMENTARY
PUBLICATIONS.)
WARNING: REFRIGERANT R12 IS USED IN S/N’s 4636001 THRU 4636186 ONLY . REFRIGERANT
HFC-134A IS USED IN S/N’S 4636187 AND UP . ANYONE SERVICING THE AIR
CONDITIONING SYSTEM MUST BE FAMILIAR WITH THE REFRIGERANT, LUBRICANT,
AND COMPONENTS USED IN THAT PARTICULAR SYSTEM.
This installation consists of a compressor with its special brackets, two evaporator modules and blowers,
a condenser, a receiver dehydrator, a manifold assembly which incorporates dual pressure switches,
high and low service ports, and related plumbing.
The evaporators filter, dehumidify and cool the air. The evaporator modules are mounted underneath the
floor between the ribs at F.S. 233.87 and F.S. 241.50 along with the blowers, expansion valves, ducting,
service ports, and related tubing.
The compressor is a five cylinder, rotary, piston type which is supported by special brackets at the
forward, left area of the engine. A V-belt connected to the starter ring gear pulley, drives the compressor
through a magnetic clutch.
The condenser is located in the aft fuselage. Air is drawn through the condenser and vented overboard
by means of a blower and duct.
The manifold assembly incorporates high and low service ports, a high pressure switch, and a low
pressure switch that control the condenser head pressure by engaging or disengaging the compressor
via a magnetic clutch.
The air conditioning system uses refrigerant HFC-134a, except in S/N’s 4636001 thru 4636186 only -
which use R-12. The refrigerant enters the compressor as a vapor. The compressor pressurizes the
heat-laden vapor until its pressure and heat reach a point much hotter than the outside air. The
compressor then pumps the vapor to the condenser where it cools and changes to a liquid. The liquid
then passes to the receiver-dehydrator. The receiver-dehydrator’s function is to filter, remove any
moisture and ensure a steady flow of liquid refrigerant into the evaporators through the expansion
valves. The expansion valves are temperature controlled metering valves which regulate the flow of liquid
refrigerant to the evaporators. Inside each evaporator the liquid refrigerant changes state to a gas and, in
doing so, absorbs heat. The evaporators then absorb the heat from the air passing over the coils. From
the evaporators, the refrigerant vapor returns to the compressor where the cycle is repeated.
NOTE: The air conditioning system should be operated at least once a month to prevent sticking valves
and to keep the system lubricated.
2. Troubleshooting
See Chart 1.