TM 9-4120-407-14
4-29. EXPANSION VALVE TESTING AND REPLACEMENT. (Cont)
The following tests must be conducted with power on and evaporator
fans operating. Exercise extreme caution to avoid personal injury.
(5) Operate the air conditioner in the COOL mode with the TEMPERATURE control set fully to
(6) Place one hand on the tubing (2). If a drop in temperature is felt on the tubing, the expansion
valve (6) is not closing fully and should be replaced.
The following test can cause the compressor to flood with liquid
refrigerant. If the air conditioner operates under the test conditions
more than a few seconds, excessive flooding of liquid refrigerant may
(7) With one hand on the tubing (2), remove the sensing bulb (3) from the container of ice water and
warm it in the other hand. If a temperature drop is not felt in the tubing by the time the sensing
bulb warms, the expansion valve (6) is not opening and should be replaced. If a drop in
temperature is felt in the tubing, immediately turn the air conditioner MODE switch to OFF
RESET.
NOTE
If the expansion valve fails any of the above tests, it is not necessary
to perform the next two procedures.
(9) Slip the sensing bulb (3) into clamps (5). Be sure the bulb is in original position and making
metal-to-metal-contact with the tubing (2). Tighten two screws (4).
(10) Install insulation (1) and wrap with insulation tape.
(1) Remove insulation (1) and (7) from tubing (2) and (8).
(2) Note position of sensing bulb (3) and loosen two screws (4).
(3) Carefully pull sensing bulb (3) out of clamps (5).
(7) Remove tube coupling (10).
(8) Remove two screws (11), spacers (12), body (13), gasket (14), cage assembly (15), gasket (16),
seat (17), and base (18).
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