(3) Remove the supply air louver. (See paragraph 4-20.)
(4) Remove the mist eliminator. (See paragraph 4-22.)
b. Testing Method. There are two acceptable methods for leak testing the refrigeration system.
(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 tester 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 observing for the formation of bubbles.
If the soap solution testing method is used, thoroughly rinse with fresh water after testing is
completed. A residual map film will attract and accumulate an excessive amount of dust and dirt
c. 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
methhod, the system may be pressurized with dry nitrogen alone.
(1) To pressurize a system that has some refrigerant charge, for either leak testing method:
(a) Remove the caps from the high and low pressure charging valves.
(b) Connect the hoses from a charging manifold to the charging valves.
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 recharge the system after this test is
(c) Connect a nitrogen pressure regulator and nitrogen bottle to the center hose connection of the
(d) Own the unit charging valves and the charging manifold valves.
(e) Open the nitrogen tank valve and pressurize the system to 350 psi (24.7 Kg/cm2).
(f) Perform leak tests.
(g) If a leak is found, discharge and purge the system and repair leak. See specific instructions for
components to be removed.