TM 9-4120-402-14
5-30. EXPANSION VALVE. - continued
WARNING
The following test must be conducted with power on. Exercise extreme caution.
CAUTION
Use suitable disconnect to isolate power source when connecting input power cable. Do not
connect power cable to unit or power source if voltage is present.
(4)
Connect power at power source.
NOTE
When performing the next step, the unit may cycle off due to the low pressure switch opening. If
this happens, turn the rotary MODE selector switch to OFF/RESET.
(5)
Set the potentiometer TEMPERATURE control to full COOL, place one hand on the exposed suction
return line, and start the unit in COOL mode. If a drop in temperature is felt on the suction return line,
the expansion valve is not closing fully and should be replaced.
CAUTION
When performing the next test, turn the air conditioner to OFF/RESET as soon as a definite drop
in temperature is felt on the suction return line. If the test conditions are continued more than a
few seconds, the expansion valve will fully open and an excessive flood-back of liquid refrigerant
(6)
With one hand still on the suction return line, remove the sensing bulb from the container and warm it
in the other hand. If a temperature drop is not felt in the suction return line by the time the sensing
bulb no longer feels cold to the hand, the expansion valve is not opening and should be replaced. As
soon as a temperature drop is felt, turn the air conditioner to OFF/RESET.
(7)
Disconnect power at power source.
b.
Replace.
(1)
Unwrap insulation from suction line so that sensing bulb is exposed. Note position of sensing bulb on
suction return line. Loosen hardware and clamps securing sensing bulb to suction return line. Pull
bulb out of clamps.
(2)
Remove screw (1), flat washer (2), lock washer (3), and nut (4). Remove clamp (5).
(3)
(4)
5-74