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TM 55-1905-219-14-11
5-144. REFRIGERATOR/FREEZER - MAINTENANCE INSTRUCTIONS
(Continued).
LOCATION
ITEM
ACTION
REMARKS
SERVICE (Cont)
(3)
The low-side refers to that part of the refrigeration system consisting of:
Suction Line
Crankcase up to the intake valve located in the valve
Plate
(4)
The high-side refers to that part of the system extending from the cylinder head, condenser, receiver
tank and liquid line up to the expansion valve.
(5)
It is evident that before testing for leaks on the low-side, it is necessary to build up a pressure on the
low-side. This is done by attaching the pressure gauge at the suction service valve and charging the system to about 30
lbs.
f.
Halide torch leak test.
A halide torch is used to detect a leak in the freon 12 refrigerant. A change of color in the flame from blue to green
indicates a leak around the joint being tested.
g.
Air in the system may be caused by one of two reasons:
(1)
By carelessness in servicing or charging methods.
(2)
By a leak in the low-side when all refrigerant leaks out allowing air to be drawn into the system when
operating under a vacuum.
(3)
Air is non-condensable under the temperature and pressure conditions existing in refrigerating
compressors. Therefore, the air becomes an inert substance which remains in the compressor head and condenser,
resulting in increased discharge pressures and reduced condenser efficiency.
(4)
If sufficient air is present, the discharge pressure will become so high that the compressor operation
will be overworked forcing the motor overload device to cut out.
(5)
To distinguish whether air in system or an overcharge of the refrigerant is causing the trouble will be
relatively easy to determine by shutting off the unit and allowing it to cool to room
5-1463


 


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