MODEL PCA090480WH
CHAPTER 3
TROUBLESHOOTING
Section 5: Helpful Troubleshooting information
3-5
March 2013
Page 88
Proprietary/Confidential
© 2013 Twist, Inc.
time check the evaporator outlet line for a rapid temperature
change, this indicates flood through of liquid refrigerant. If
refrigerant floods through the valve, the power assembly
operates properly.
U
WARNING
U
: DO NOT FLOOD BACK THROUGH SUCTION LINE FOR
AN EXTENDED PERIOD SINCE EXCESSIVE LIQUID
FLOOD BACK MAY DAMAGE THE COMPRESSOR.
B.
Valve Stuck in Open Position
If the expansion valve is stuck in an open position, there will be an
excessive amount of sweating on the suction line and compressor
crankcase due to the large amount of liquid being passed into the
suction line. In units with sight glass in the compressor crankcase,
excessive foaming will be seen.
C.
Valve Stuck in Closed Position
A warm supply air temperature may indicate an expansion valve that is
stuck. When this happens, the suction pressure will be low.
D.
Bulb
Miss-Located
Clamp the expansion valve bulb to the horizontal suction line near the
evaporator outlet. Clean the suction line thoroughly before clamping the
remote bulb in place. Install the remote bulb at the position of about 4
or 8 o'clock. After clamping it to the line, thoroughly insulate it with
material that will not absorb moisture.
E.
Moisture in Valve
Water or a mixture of water and oil frozen in the valve port or working
parts of the valve will prevent proper operation.
This is a common source of trouble on expansion valves. Since the
valve is the first cold spot in the system, moisture will freeze and block
the valve open, closed, or in any position in between. (See “B” and “C”
above.)
Property of American Airlines
