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

Page: 343 / 1956

PAGE 25
Feb 28/07 2E17
21-50-00
PIPER AIRCRAFT, INC.
PA-46-350P, MALIBU MIRAGE
MAINTENANCE MANUAL
F. Servicing the System (with a Manifold Set)
(1) Test Gauge and Manifold Set
The proper testing and diagnosis of the air conditioning system require that a manifold gauge
set (or a charging stand) be attached to 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 7 and 8.)
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 or 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 systems to the middle
service port of the manifold set. This is desirable only when it is necessary to let refrigerant out
of or into the system. (See Figures 7 and 8.)
(2) Evacuating the System (See Figure 9.)
(a) Ascertain that all system pressure is released.
(b) Connect the manifold set hoses to the service ports and vacuum pump as shown in
Figure 9.
(c) Close the high side (pressure) and low side (suction) hand valves on the manifold set.
(d) Start the vacuum pump.
(e) Open the low side manifold set hand valve. The low side gauge should show a vacuum.
(f) After five minutes of pump operation the high side gauge should indicate slightly below
zero. If it does not, stop the pump and eliminate the blockage in the system by replacing
the faulty component, then repeat the previous evacuation steps.
(g) Operate the vacuum pump for fifteen minutes or until the low side gauge indicates 24 to
26 In. Hg. whichever occurs first.
(h) Close the low side hand valve, stop the vacuum pump and observe the low side gauge. If
the gauge rises at a rate faster than 1 In. Hg. in 5 minutes, there is a leak in the system.
Locate and repair the leak (per the following instructions), then repeat the previous
evacuation steps.
(i) With both the low and high side valves open, continue the pumping and hold the system
below 26 In. Hg. for a minimum of 30 minutes. All the previous pumping time may be
included in the 30 minutes provided that no leaks or blockages are noted, and provided
that the system is not opened by removal or disconnection of components.
(j) Close the low and high side hand valves, stop the vacuum pump and perform the
charging procedure immediately.
(3) Leak Detection (See Figure 10.)
(a) Close both the low side and high side valves on manifold hand set.
(b) Disconnect manifold hand set middle port (yellow) hose from low side port on charging
stand and connect it to a container of R12 or HFC134a refrigerant, as appropriate.
(c) Open refrigerant container service valve.
(d) Open the manifold hand set high side valve until a pressure of 50 psig is reached on low
side gauge. Close high side valve.
(e) Locate leak(s) using an electronic leak detector designed to detect R12 and/or R134a
refrigerant, as appropriate. Or, use soap and water in a thick solution.