Piper Arrow IV, Maintenance Manual

Page: 137 / 752

SERVICE VALVE REPLACEMENT.
The valves on the York compressor are sealed with a gasket placed in the valve port boss. Lubricate the
gasket with refrigerant oil of the type used in the compressor, place the valves with the tube fitting facing aft
and secure with .312 bolts, torque to 15-23 inch-pounds.
—NOTE—
Whenever the air conditioning refrigerant lines or system is
opened for any reason, the lines and fittings should be capped
and sealed immediately to prevent dirt and other contaminants
from entering the system. (It is not advisable to put a plug into
the hoses or fittings.)
TEST GAUGE AND MANIFOLD SET.
The proper testing and diagnosis of the air conditioning system require that a manifold gauge set be
attached into the system. This set consists of two gauges mounted to a manifold. One gauge is a high pressure
gauge used in the discharge side of the system. The other is a low pressure gauge used in the suction side of
the system. The manifold is a device having fittings for both gauges and connection hoses with provisions for
controlling the flow of refrigerant through the manifold. (See Figures 21-6 and 21-7.)
The center port of the manifold set is used for charging or evacuation procedures, or any other service that
may be necessary.
Both the high and low side of the manifold have hand shut-off valves. When the hand valve is turned all
the way in, in a clockwise direction, the manifold is closed. The pressures on the side of the system will,
however, be recorded on the gauge above the hose.
Cracking the hand valve, in the counterclockwise direction, opens the system to the middle service port of
the manifold set. This is desirable only when it is necessary to let refrigerant out or into the system. (Refer to
Figures 21-6 and 21-7.)
CHECKING THE SYSTEM FOR LEAKS.
There are several methods of doing this operation, depending on the type of equipment which is available.
Two methods of performing this check will be covered in the following paragraphs.
—NOTE—
Evacuate system prior to leak check.
21-50-07
Page 21-18
December 1, 1978
1F17
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL