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TM5-4120-387-14
(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 ±O.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 5-25) before proceeding with quench valve test.
NOTE
Except in a very hot. climate, with room air temperature above
90°F (32.2°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 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°F (4.4°C).
(7) Compare the saturation temperature with indicated temperature. The
indicated temperature should be 25 ±5°F (13.9 ±2.2°C) higher than the saturation
temperature. For example:
With a 40° saturation temperature, the thermometer
should read 65 ±5°F.
If indicated temperature is not within above limits, quench
valve is not functioning properly and should be adjusted.
NOTE
If valve does not need adjustment, skip (8) below.
(8) If the superheat setting is not within the limits shown above, adjust
the liquid quench expansion valve as follows:
(a) Remove the hexagonal seal cap from the side of the power assembly.
(b) Turn the adjusting stem two complete turns to change the superheat
setting by 1°F (0.55°C).
Turn the stem clockwise to increase superheat span;
counterclockwise to decrease it.
Do not change more than two full turns at one
time, then wait at least 2 minutes for temperature to stabilize and recheck
pressure and temperature before further adjustment.
If valve cannot be properly
adjusted, replace the valve.
(c) When the proper setting is obtained, install the seal cap.
(9) Turn unit OFF.
(10) Remove thermometer.
(11) Cover the sensing bulb and suction line with insulation tubing that
was removed in step (2) above.
Secure tubing in place using tape, item 11,
Appendix E.
5-45
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