Test Gauge And Manifold Set - Piper Navajo PA-31 Service Manual

COMPOUND
PRESSURE GAGE
C
TO SUCTION
SERVICE VALVE
PIPER NAVAJO SERVICE MANUAL
408
HIGH PRESSURE
GAGE
TO DISCHARGE
SERVICE VALVE
TO VACUUM PUMP OR
REFRIGERANT CYLINDER
Figure 14-29. Test Gauge and Manifold Set
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 that 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 14-28, 14-29 and 14-30.)
14-69. 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.
14-70. LEAK CHECK - METHOD I. (EVACUATE PRIOR TO LEAK CHECK)
a. Connect the manifold gauge, set into the system and determine if there is any refrigerant in the
system. A minimum of 50 psi refrigerant pressure in the system is needed for leak detection. (Refer to
Figure 14-30.)
b. Purge the hoses of air by allowing some refrigerant to escape from the connections at the service
valves. Then tighten connections at the service valve.
c. Close the low side manifold valve and open the high side manifold valve. (Refer to Figure 14-28.)
d. Open the refrigerant container service valve and allow the pressure at the low side gauge to reach
50 psi, at which time close the high side manifold valve.
e. Close the refrigerant container service valve and remove the hose if no leaks are evident.
f. It is advisable to use an electronic leak detector to check this system instead of an open flame
leak detector due to the possible presence of gasoline fumes in the engine nacelle.
Reissued: 10/12/79
ACCESSORIES AND UTILITIES
5G11