TM 9-4120-357-14
NOTE
If cylinder is equipped with both liquid and gas (vapor) valves,
connect the line to the liquid valve.
(b) Weigh the cylinder, and record the weight.
(c) Open the discharge line service valve, and slightly open the refrigerant cylinder shutoff valve. Liquid re-
frigerant 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 re-
frigerant 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 additional warm up time.
(9) With power connected to the air conditioner, turn the mode selector switch to cool, and turn the temperature
control thermostat to maximum decrease position. Temporarily prop the front access panel across the opening. With the
compressor operating, observe the sight-glass liquid indicator. If bubbles or milkiness appear, top off the refrigerant
charge as follows:
(a) Connect a cylinder of refrigerant, R22, loosely to the gauge 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.
(b) 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.
(c) When liquid in sight-glass indicator runs clear and free of bubbles, close the suction line service valve and
the cylinder shutoff valve.
(d) Disconnect the refrigerant cylinder, and replace the caps on both service valves.
i. Final Assembly. After replacement of the high and low pressure switches is complete, and the refrigeration sys-
tem is recharged, replace the front access panel as follows:
(1) Position the front access panel on the air conditioner with the lower edge behind the stop of the base plate, and
push the panel into an upright position.
(2) Secure the panel with four panel fastener screws.
5-17. Solenoid Valves.
There are two solenoid valves, K3 and K4, in the refrigerant control system. (See Figure 1-5.) Both valves are normally
open, and close only when energized by the control circuit. Valve K3 is located in the bottom of the air conditioner, be-
tween the compressor and the junction box. Valve K4 is located in the evaporator fan intake compartment beside the
right-hand accumulator tank, R3. When malfunction of the valves is not due to failure of the electrical coil or internal
operating parts, the faulty valve must be replaced. Replacement procedures are the same for each solenoid valve, ex-
cept for access. Proceed as follows:
a. Access.
rator intake grille, and removing the grilles.
5-23
