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TM 5-4120-361-14
Section III.
GENERAL MAINTENANCE
5-5.
General.
This section contains general servic-
ing instructions that otherwise would
have to be repeated several times in
this manual.
5-6.
Testing for Leaks.
The air conditioner can be tested for
refrigerant leaks by the use of an elec-
tronic leak detector, by the halide test
or by the soap bubble method.
The pre-
ferred method is use of the electronic
leak detector.
If sufficient pressure
is not present in the system to accom-
plish an adequate leak test, add dry
nitrogen at the receiver charging valve
to increase the system pressure to 300
psig, then conduct the leak test. If
the system is totally discharged, to
conserve leak test refrigerant, pres-
surize the system with R-12 to 72 psig,
isolate the compressor by front-seating
the service valves (1 and 2, figure
3-2).
At the receiver charging valve
pressurize the system with dry nitrogen
to 300 psig, then conduct the leak
test.
(1) By Electronic Leak Detector.
Using a G.E. Type H-2 Leak Detector, or
equivalent, proceed as follows:
(a) Turn on and calibrate the
leak detector as described in the in-
structions supplied with the instru-
ment.
(b) Slowly pass the detector
probe tip over the sweat fittings, mech-
anical couplings and valves in the re-
frigerant circuit.
If refrigerant is
leaking, detector will provide a visible
or audible signal.
(c) Use the soap-bubble method to
localize the leak to a defective com-
ponent or connection.
(2) By Halide Leak Test. Using a
propane flame halide leak detector, pro-
ceed as follows.
(a) Slowly pass the exploring
tube on the torch over the sweat fit-
tings, mechanical couplings and valves.
If refrigerant is leaking, the flame
will be affected as follows:
INSTRUCTIONS
Small leak -- flame changes from
blue to green
Large leak -- flame changes from
blue to dense blue
with reddish tip
Massive leak- may extinguish flame
(b) Use the soap-bubble method to
localize the leak to a defective com-
ponent or connection.
(3) By Soap Solution Method.
Using
either a prepared bubble-type leak de-
tector compound or a solution of hand
soap in water, proceed as follows.
(a)
Apply the solution to all
points of possible leakage, and watch
for bubble formation indicating a re-
frigerant leak.
NOTE
Allow solution to remai
joints long enough for
leaks to form noticeab
bles.
n on
small
e bub-
(b) Wipe solution from joints and
mark spots where leakage is observed.
5-7.
Refrigeration System.
a.
Opening System.
When the refrig-
eration system must undergo maintenance
that requires the system to be opened
for removal of parts, the system must
first be discharged (para 6-3).
After
the repair has been made and all solder-
ing completed, the system must be tested
for leaks and charged (para 6-3).
b.
Removal of Parts.
When the re-
frigeration system must undergo main-
tenance that requires the refrigerant
system to be opened for removal of
parts, the system must first be dis-
charged and purged (figure 6-1).
After
the repair has been made and all solder-
ing completed, the system must be tested
for leaks and charged (para 6-3). Ex-
cept for flare nut connection, all the
tubing attachments in the refrigeration
system are “sweat-joints” which are
opened by heating with a brazing torch.
During unseating, shield the wiring,
insulation, painted metal, and valves
from the heat of the torch.
Use wet
5-6
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