TM 9-4120-357-14
(b) Halide Torch. Turn on the gas from the cylinder and light the torch. Adjust to obtain a stable light-blue flame.
Pass the open end of the sensing tube slowly around all locations at which a leak could exist. A small leak will be indi-
cated by the flame turning from blue to indigo with a red tip, or the torch may be extinguished.
(c) Soap Solution. With the air conditioner in operation. Brush soap solution on all possible points of leakage, and
watch for bubbles. Follow a definite sequence to avoid missing any points that should be tested. Wipe the solution from
all joints, and mark any point at which a leak is found.
(5) Discharge the system in
accordance with paragraph 5-6. If
leaks are detected, repair and retest as
directed
above. If system is leak-tight, proceed as follows:
(a) Connect a vacuum pump to the suction service valve gage port, and a vacuum gage to the discharge service
valve gage port. Start the pump, and open both service valves. Operate the vacuum pump until pressure in the system
is reduced to not more than 500-Microns. Close the suction line service valve, and turn the vacuum pump off. Let the
unit stand in this condition for at least three hours. If the system holds the vacuum without changes, continue with step
(b) . If 500-Micron vacuum cannot be held for three hours, break the vacuum with dry nitrogen and retest for leaks. If
500-Micron vacuum cannot be achieved, one or more of the following reasons may account for the problem:
1. Leaks in the refrigeration system. Break vacuum with dry nitrogen, and retest for leaks.
2. Leaks in the refrigeration system. Break vacuum with dry nitrogen, and retest for leaks.
3. Internal leakage of vacuum pump. Test pump by blocking off vacuum pump intake and continuing to pump. If
the pump still fails to reach 500-Microns, the pump is faulty.
(b) With the suction line service valve closed, disconnect the vacuum pump and attach a
cylinder of
dry nitrogen.
Leave the connection to the suction service valve loose, and open the cylinder shutoff valve for a few seconds to purge
the line of air. Tighten the connections, and crack the suction line service valve open slightly to break the vacuum.
Leave in this configuration until system reaches atmospheric pressure (760 MM) , then close the suction service valve
and cylinder shutoff valve, and disconnect the nitrogen cylinder.
(c) Reconnect the vacuum pump to the 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 remove 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 shut-
off valve for a few seconds to purge the line of air. Tighten the service valve connection. Charge 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 beamscale, with the valve end down.
2. Weigh the cylinder, and record the weight.
3. Open the discharge line service valve, and slightly open the refrigerant cylinder shutoff valve. Liquid refriger-
ant 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 dis-
charge 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 opera-
tion in COOL mode. If knocking or pounding is heard at start of COOL mode, turn selec-
tor switch to OFF or VENTILATE at once and allow additional warm up time.
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