MODEL PCA090480WH
CHAPTER 3
TROUBLESHOOTING
Section 5: Helpful Troubleshooting information
March 2013
3-5
Proprietary/Confidential
Page
87
© 2013 Twist, Inc.
A.
Roll out the aircraft service hose and attach an airflow restriction device
to the aircraft coupler.
B.
Start the unit and after the outlet damper is fully open, restrict the outlet
area of the aircraft coupling to 25 percent.
C.
Cause all compressor systems to operate.
E.
Connect the low-pressure gauge of a service manifold to the Schrader
valve on the suction line and read the pressure. Restrict the air flow
until the gauge reads 50 psia.
E.
Feel the hot gas line downstream of the hot gas valve. It should be hot.
The valve should start to open at 52 psia.
G.
The valve can be adjusted by the spring tension on top of the valve.
Adjust the airflow to get the suction pressure higher or lower to test the
hot gas valve setting.
G.
Remove the service gauge manifold connection and cap the Schrader
valves. Return the unit to service.
8. Expansion
Valve
Malfunction
A.
Charge
Lost
The power element of an expansion valve consists of the remote bulb,
capillary tube, and the bellows or diaphragm which actuates the valve
cage. If this power element is inoperative or has lost its charge, the
valve will either maintain an almost closed position or may close
completely. To test for an inoperative power element:
(1)
Stop
compressor.
(2)
Remove remote bulb from contact with suction line.
(3)
Place bulb in ice water.
(4)
Start
compressor.
(5)
Remove bulb from ice water and warm in hand. At the same
Property of American Airlines
