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TM 5-4120-270-15
certain to cover all the repaired area. Replace broken
terminal lugs with exact duplicates.
d. Replacement. Replace single wire by using exact
duplicates of terminal lugs from old wire.
If the wire is part of a harness assembly, disconnect the
wire at both ends and tape ends. Attach the replace-
ment wire to the outside of the harness with PVC
electrical tape. Refer to figure 1-6 for practical wiring
diagrams
.
Section II. REFRIGERANT SYSTEM
6-13. General
This section contains those items which are considered
part of major components or auxiliaries of the air
conditioner
refrigerant
system.
They
consist
of
expansion valves, solenoid valves, pressure sensing
valves and switches, compressor assembly, electric
motors and refrigerant tubing.
6-14. Pressure Testing Under Normal
Operating Conditions
If the air conditioner is losing cooling capacity, or is in
some. way not functioning properly, a check of
refrigerant system operating pressures will frequently
lead to cause of malfunction. Install pressure gages on
gage ports of suction and discharge line access valves
(fig. 5-11) and turn valves two turns to open, exposing
gages to system pressure. Start air conditioner and
compare gage readings with normal ranges or system
pressures listed in table 61.
Table 6-1. Normal Operating Pressures
AMBIENT-
DEGREES F
50ƒ
75ƒ
100ƒ
125ƒ
90ƒF DRY-BULB
RETURN AIR
TO UNIT
Suction line (psig)
58-65
58-70
60-75
75-90
Discharge line
125-
160
175-
120
255-
295
370-
410
(psig)
80ƒF DRY-BULB
RETURN AIR
TO UNIT
Suction line (psig)
58-65
58-70
60-75
65-75
Discharge line
120-
155
170-
205
250-
290
370-
410
(psig)
Note. Dry-bulb temperatures are measured with an
ordinary thermometer.
6-15. Leak-Testing Refrigerant System
a. Electric or Halide Torch Leak Detector. The
preferred method of testing for leaks in the refrigerant
system is by using a halide torch. A halide detector is
used by passing the exploring tube over sweat-soldered
fittings, all mechanical couplings, and valves. If
refrigerant is leaking from the system, the flame of the
halide torch will change from blue to green when the leak
is small. If the leak is large, the flame will be dense blue
with a reddish tip; or, a large leak may extinguish the
torch. Mark all spots where leaks are detected. Drain
the refrigerant system and repair the leak, and pressure
test (para 6-28, 29, 30).
Warning: Avoid bodily contact with liquid refrigerant
and avoid inhaling refrigerant gas. Be especially
careful that Refrigerant-22 does not come in contact
with the eyes. In case of refrigerant leaks, ventilate
the area immediately.
b. Soap
Solution
Method.
Operate
the
air
conditioner, brush all possible points or leakage
with soap solution, and watch for bubbles. Follow
a definite sequence so all points will be thoroughly
tested. Wipe the soap solution from all joints and
mark any spot where a leak occurs. Drain the
refrigerant system and repair leaks and pressure
test (para 6-28, 29, 30).
6-16. Refrigerant Tubing and Fittings
a. The refrigerant tubes used on the air conditioner
consist of copper tubing and the necessary fittings. The
joints of the refrigerant tubes are soldered. Inspect the
tubing for cracks and breaks. Replace any defective
tubing with tubes of the same length, size, shape, and
material. Test the installation of tubes and fittings for
leaks. Replace rubber insulation as necessary. Note. If
the refrigerant system has been open to the atmosphere,
replace the dehydrator (para a-31). Pressure test and
evacuate the system before charging (para -28, 29, 30).
b. If the refrigerant system must be opened for
repairs or replacement of parts, open the suction line
access valve and relieve the system pressure. Connect
a hose line to the suction line access valve and purge the
refrigerant to an outside area.
Warning:
Avoid
bodily
contact
with
liquid
Refrigerant-22 and avoid inhaling refrigerant gas. Be
especially careful that Refrigerant-22 does not
contact the eyes. In case of refrigerant leaks,
ventilate the area immediately.
c. After purging the system allow the tubing to warm
to ambient temperature before opening the system; this
delay will help prevent the for-
6-11
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