b. When to Test. The entire repaired area should be thoroughly leak tested after repair or
replacement of any component, before it is recharged with refrigerant 22. Leak testing is also
the method for troubleshooting when a system has lost all or part of its refrigerant charge
through an undetermined cause.
There are two acceptable methods for leak testing the refrigeration
c. Testing Method.
(1) Refrigerant gas leak detector. If an electronic refrigerant gas leak detector is
available, it should be used in accordance with the procedures contained in
TM 9-4940-435-14, Leak Detector, Refrigerant Gas.
The electronic refrigerant gas leak detector is highly sensitive to the
presence of a minute quantity of gas in the air, and due to this factor
is quite effective in the detection of small leaks. However, due to the
rapid dispersion of refrigerant gas into the surrounding air, difficulty
may be encountered in pinpointing large leaks. The detector must be
used in a well ventilated but draft-free area.
(2) Soap solutions. In this method, a strong solution of a liquid detergent and water
is brushed onto all points of possible leakage while closely watching for the
formation of bubbles.
If the soap solution testing method is used, thoroughly rinse with fresh
water after testing is completed. A residual soap film will attract and
accumulate an excessive amount of dust and dirt during operation.
d. Testing Procedures. To perform leak testing by use of the electronic detector, it is
necessary that the system be pressurized with a proportion of refrigerant gas. To perform leak
testing by use of the soap solution method, the system may be pressurized with dry nitrogen
(1) To pressurize a system that has some refrigerant charge, for either leak testing
(a) Remove the hose connection protective caps from the high and
low pressure service valves.
(b) Connect the hoses from a charging manifold to the service
If it is possible that the problem may not be a leak and that you may
not have to replace a refrigeration system component, refrigerant 22 may
be substituted for the nitrogen in the following test. If nitrogen is used,
you will have to discharge, evacuate and re-charge the system after this
test is completed.