TM 9-4120-403-14
Inspection
(1) Inspect for kinked, or otherwise damaged capillary line, and loose or missing mounting hardware.
(2) Check thermal bulb to see that it is securely clamped to the suction line.
Test
NOTE
The expansion valve as supplied with the unit is preset at the factory. This valve should not be adjusted.
(1) Perform a refrigerant pressure check on unit in accordance with paragraph 5-13. Leave gages or service
manifold attached.
(2) Remove the suction line insulation from the area of the sensing bulb. Observe location and position of bulb for
reinstallation.
(3) Loosen the screws and nuts in the bulb straps that attach the sensing bulb to the suction line, and pull the bulb
out of the straps.
CAUTION
Use care to not damage or kink the capillary.
(4) Place the sensing bulb in a container of ice water or crushed ice so that it is reduced to a temperature near
32 (0 ).
F
C
(5) Set TEMPerature control thermostat knob fully DECREASE (counterclockwise), fan speed to LO SPEED, place
one hand on the exposed suction return line, and start the air conditioner 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. If the return line temperature
remains constant, check the pressure gage; it should indicate approximately 59 +/-2 psi (4. 0 +/-0. 14 kg/cm2). If the
pressure is not within the above limits, test the operation of the quench valve (para 5-16) and the pressure regulator
valve (para 5-26) before attempting replacement of the evaporator expansion valve.
CAUTION
When performing the next test, turn the air conditioner to OFF 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 may damage or destroy the
5-41