Piper Arrow IV, Maintenance Manual

Page: 162 / 752

EVAPORATOR ASSEMBLY INSTALLATION.
1. Cement gasket in place on the flanges of the evaporator housing and attach the large end of the
mounting gasket to the back of the housing.
2. Install the housing through the access hole with the air duct outlet on top. Mate the mounting flanges
to the mating surface of the mounting panel and insert the screws. (Do not tighten at this time.)
3. Line up the mounting bracket with mating holes in mounting panel; insert screws and tighten. Tighten
screws in the flange at this time. Be certain gasket is in place. The flange must have an air tight seal.
4. Couple the suction and discharge lines to their respective fittings (apply Loctite refrigerant sealant to
tube flanges only).
5. Evacuate and charge system. (See Evacuating the System and Charging the System.)
6. Check for leaks (see Checking the System for Leaks) if no leaks are detected. Seal and install access
panel on evaporator housing.
7. Couple flexible air duct and drain tube.
8. Make and check electrical connections.
9. Check operation of blower and refrigerant systems.
10. Install rear bulkhead panels. Be certain to seal. (See NOTE.)
—WARNING—
Whenever it is necessary to remove and replace the cabin rear
panel, it should be replaced and sealed in the original manner to
prevent exhaust gases from entering the cabin. After removing
and replacing the rear panel, conduct a carbon monoxide test on
the ground and in flight with and without the air conditioner
operating. Presence of C02 shall not exceed one part in 20,000.
PRESSURE RELIEF SWITCH. (Ranco)
The pressure relief switch automatically prevents the system from over-pressurization by breaking the
electrical circuit to the magnetic clutch, stopping the compressor until pressure is reduced. The switch is
located in the line between the receiver and expansion valve, and set to cut out at 350 ± 10 psi and cut in at 250
± 10 psi.
—NOTE—
Before the relief switch is removed, the air conditioning system
must be discharged. (See Discharging.)
ELECTRICAL INSTALLATION.
The electrical system, routing and component are installed and routed in the conventional aircraft manner.
The wiring harness is connected to switches in the climate control center on the right side of the instrument
panel. The harnesses cross the instrument panel to the left side where two wires are taken off for the
compressor clutch. The harness then passes aft along the left side of the fuselage where it connects to the
blower motor, pressure relief switch and the condenser actuating motor.
21-50-41
Page 21-43
December 1, 1978
1G18
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL