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TM 5-4120-259-15
CHAPTER 6
REPAIR INSTRUCTIONS
Section I. REFRIGERANT SYSTEM
92. General
Refer to refrigerant flow diagram, figure
27. Liquid refrigerant which has been admit-
ted to the evaporator absorbs heat from the
air drawn over and around the evaporator
coil. This cooled air is blown out into the area
being conditioned. Upon absorbing heat, the
refrigerant in the evaporator boils to a gas
which is drawn to the compressor. The com-
pressor raises the pressure and temperature of
the gas and discharges to the condenser where
the gas condenses to liquid. Heat from the gas
is absorbed by the condenser coil surfaces and
is carried away by air that is drawn over and
round the condenser coil. The liquid refriger-
ant is accumulated in a receiver and is re-
leased to the evaporator by the solenoid valve
when the valve is actuated by the thermostat.
The thermal expansion valve senses the heat
of the refrigerant leaving the evaporator, and
controls the flow of liquid refrigerant to the
evaporator to prevent flooding. The hot gas
bypass creates a refrigerant circuit bypass
which permits la continual operation of the
compressor.
93. Testing for Refrigerant Leaks
a. Using Leak Detector. Proceed as fol-
lows:
(1)
(2)
(3)
Make sure that the testing unit is
working correctly.
Hold the exploring hose close to the
joint being tested, to prevent dilu-
tion of the sample by stray air cur-
rents.
Move the exploring tube slowly
around each joint. Allow time for
detector to react to very small leaks.
(4) Follow a definite order in leak test-
ing so that no joints will be missed.
Use soap suds as necessary to find
the exact point at which a leak is
occuring.
Note. Do not use a leak detector in an
atmosphere known to be heavy with B
frigerant m this condition will tend to
foul it.
b. Using Soap Suds. A soap suds test is
preferred in an area which is contaminated
with refrigerant. Such a tsst will also permit
a more exacting location of small leaks. To
prepare suds for testing, use a soap and water
solution which can be worked into a lather.
Glycerine added to the solution will cause the
lather to remain wet longer. Where applying
soap suds, paint the lather on the joint all the
way around,
and then examine the joint
thoroughly for bubbles. Use a mirror to ob-
serve any part of the joint not directly visible.
It will sometimes take a full minute or more
for bubbles to appear at a small leak. Ques-
tionable spots should be covered with lather
and examined again.
94. Discharging the Refrigerant System
a. General. Prior to opening the refrigerant
system for maintenance, the system must be
discharged. The refrigerant may be discharged
into a suitable service cylinder for reuse or
discharged to the atmosphere.
Warning: Refrigerant-22 is contained in the
refrigerant system under high pressure. Ex-
treme care must be exercised to prevent re-
frigerant from coming in contact with ex-
posed skin and eyes. Provide adequate ventila-
tion when discharging the system in a confined
area.
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