TM 9-4120-357-14
(c) Reconnect the vacuum pump to other suction line service valve gage port, and start the pump.
Open
the suction line service valve, and again pump until a 500-Micron vacuum is achieved. This double evacuation will re-
move all traces of water vapor from the system. Close the suction line service valve, and disconnect the vacuum pump.
Close the discharge line service valve, and remove the vacuum gage.
(d) Connect a cylinder of refrigerant, R22, loosely to the discharge line service valve, and open the cylinder
Bag shutoff valve for a few seconds to purge line of air. Tighten the service valve connection. Charge the refrigeration
system as directed in the following steps:
1. Place the refrigerant cylinder on a scale of sufficient capacity, with the shutoff valve down, or suspend
the cylinder from a spring scale or beam scale, with the valve end down.
NOTE
If cylinder is equipped with both liquid and gas (vapor) valves, connect
the line to the liquid valve.
2. Weigh the cylinder, and record the weight.
3. Open the discharge line service valve, and slightly open the refrigerant cylinder shutoff valve. Liquid
refrigerant will be sucked into the refrigeration system rapidly at first, then more slowly as pressures begin to equalize.
When 25 pounds (11.4 KG) of refrigerant have flowed into the refrigeration system, as indicated by the scale, close the
discharge line service valve and the cylinder shutoff valve.
WARNING
Hearing protection must be worn when maintenance is performed
while air conditioner is in operation. Failure to heed this warning
can result in hearing loss or injury.
CAUTION
Connect power to unit as soon as possible after charging or any
period when power has been disconnected. Allow heater time to
vaporize refrigerant in compressor before operation in COOL
mode. If knocking or pounding is heard at start of COOL mode,
turn selector switch to OFF or VENTILATE at once and allow addi-
tional warm up time.
(e) With power connected to the air conditioner, turn the mode selector switch to cool. Turn the temperature
control thermostat to its maximum decrease position. Temporarily prop the front access panel across the opening. With
compressor operating, observe the sight glass liquid indicator. If bubbles or milkiness appear, top off the refrigerant
charge as follows:
1. Connect a cylinder of refrigerant, R22, loosely to the gage port of the suction line service valve. Open
the cylinder shutoff valve for a few seconds to purge air from the line. Tighten the connection. Leave the cylinder up-
right, or connect line to vapor valve.
2. With the air conditioner compressor operating, open the suction line service valve and the cylinder
shutoff valve to charge refrigerant gas into the system, while observing the sight-glass liquid indicator.
3. When liquid in sight-glass indicator runs clear and free of bubbles, close the suction line service valve
and the cylinder shutoff valve.
4. Disconnect the refrigerant cylinder. Replace the caps on both service valves.
f. Final Assembly. Replace the appropriate grilles and panels on the air conditioner as follows:
(1) Position the front access panel on the air conditioner by placing the lower edge behind the step of the base
plate, and pushing the panel into contact with the casing. Secure with four panel fastener screws.
(2) Position two evaporator intake grilles on the front of the air conditioner, and secure with 12 screws and' wash-
ers in the frame of each grille.
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