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 TM 9-4120-430-14
0052 00
WARNING
Ensure power source is disconnected.
TEST
Liquid Line Solenoid Valve (2, figure 1)
NOTE
This is a test for valve operation. The valve functions in COOL mode to control cooling
output of unit by supplying liquid refrigerant to the cooling coil (evaporator).
1.
Operate the unit in COOL mode and observe (evaporator) supply air temperature.
2.
With temperature selector in coolest position, the supply air temperature should be cold (approximately 15
degrees F below ambient).
3.
With the temperature selector in warmest position, the supply air temperature should be same as ambient
temperature or 1 or 2 degrees warmer.
4.
When the unit is operating as in step 2 above, but with supply air temperature not cold, remove top cover (WP 0018
00) and check solenoid coil by removing the solenoid coil to feel the magnetic attraction of the coil to the valve.
5.
If no magnetic attraction of coil to valve, problem is electrical and not the solenoid valve.
6.
If observations in step 2 and step 3 are not stated, solenoid valve is defective and must be replaced.
Hot Gas Bypass Valve (11)
NOTE
This is a test for valve operation and the maintenance of suction refrigerant pressure above 50
psig (freezing temperature) to prevent evaporator coil freeze-up.
1.
Connect service gauges to service valve and observe system pressure when operating in the COOL mode with
temperature selector switch in the coolest position.
2.
Block indoor air return and note refrigerant suction pressure reading.
3.
Suction pressure should be above 55 psig under normal operation and blocked indoor air return conditions.
4.
If suction pressure is above 55 psig under normal operation and below 55 psig under blocked indoor air return
condition, adjust the valve as follows:
a.
Remove top rear cover and large valve cap on top of valve to expose adjustment stem. Turn adjustment stem
clockwise until suction pressure is above 55 psig.
b.
If adjustment does not result in the suction pressure above 55 psig, valve is defective and must be replaced.
0052 00-2
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