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 quench 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
re-installation.
(3) Attach an accurate thermometer to an exposed surface of the suction line adjacent to the sensing bulb; use a
(4) Check that service valve and gage connection to low (suction) side are open. Note pressure indicated on gage
and temperature indicated on thermometer.
(5) Set the TEMPerature control thermostat knob to full INCREASE (clockwise). Start the air conditioner in COOL
mode. Note that suction pressure drops to 58 +/-2 psig (4. 0 +/-0. 2 kg/cm2). Allow compressor to run for at least 20
minutes. If pressure is not within above limits, test operation of pressure regulating valve (para 5-26) before proceeding
with quench valve test.
NOTE
Except in a very hot climate, with room air temperature above 90 (32. 20C), the refrigeration system
F
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 quench valve.
(6) Observe that temperature indicated remains stable for a minimum of two minutes, then find saturation
temperature for pressure indicated on gage, using table 5-1. For example: The saturation temperature for a refrigerant
pressure of 69 psig (4. 85 kg/cm2) is 40 (4. 40C).
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5-46