THE NEW PIPER AIRCRAFT, INC.
PA-32-301FT / 301XTC
MAINTENANCE MANUAL
PAGE 26
Jun 1/03
2D14
21-50-00
(3) Evacuating the System (refer to Figure 9)
NO
TE: Perform a Leak Detection check, above, before evacuting the system.
If the system has been operated in a discharged condition or anytime the system has been
open to atmospheric pressure, the receiver-dehydrator must be replaced and the system
evacuated to remove any trapped air and moisture which has entered it. A vacuum pump
capable of pulling 29 inches of mercury or better should be used. As the pressure in the air
conditioning system is lowered, the boiling temperature of the water (moisture) that may be
present is also lowered. This then forces any moisture, in the form of water vapor, out of the
system. Chart 4 demonstrates the effectiveness of moisture removal under a given vacuum.
(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, then repeat the previous evacuation steps.
Evacuation Hookup
Figure 9
To Next Page
Loading...
Need help?
General