TM 9-4120-399-14
5-21. LIQUID QUENCHER EXPANSION VALVE.
This Task Covers:
a. Removal
b. Test
c. Installation
Initial Setup:
Tools Required
Tool kit, Refrigeration
Material's Required
Insulation tape (Appendix E, item 24)
Thermal mastic (Appendix E, item 23)
Equipment Condition
Air conditioner shut down and cool,
Front panel removed (See para. 4-20).
Refrigerant system discharged (See para. 5-7).
a. Test.
(1) Perform a refrigerant pressure check on unit in accordance with paragraph 5-13.
Leave gages or service manifold attached.
(2) Unwrap insulation tubing from compressor suction line so that sensing bulb and an
adjacent section of the suction line is exposed.
(3) Attach an accurate thermometer to an exposed surface of the suction line adjacent
to the sensing bulb. Use a small amount of thermal mastic (Appendix E, Item 23) to improve
(4) Check that gage connection to low (suction) side is open. Note pressure indicated
on gage and temperature indicated on thermometer.
(5) Set the Temperature Control thermostat knob to full WARMER (clockwise). Start the
air conditioner in COOL mode. Note that suction pressure drops to 58 2 psig (4.0 0 . 2
limits, test operation of pressure regulating valve (para. 5-20) before proceeding with liquid
quencher expansion valve test.
NOTE
Except in a very hot climate, with room temperature above 90 deg. F
(32.2 deg. C), the refrigeration system will be in a bypass cycle with a
maximum volume of hot discharge vapor being recirculated back to
suction side of compressor through pressure regulator valve and liquid
quencher expansion valve.
