TM 9-4120-371-14
(b) Connect the hoses from a charging manifold to the service valves.
NOTE
If it is possible that the problem may not be a leak and that you may not have to
replace a refrigeration system component, refngerant22 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 completed.
(c) Connect a nitrogen pressure regulator and nitrogen bottle to the center hose connection of the
charging manifold.
(d) Open the unit service 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.
(h) If a leak was not found and refrigerant-22 was used to pressurize the system, see charging
(2) To pressurize a system that has been discharged and purged for leak testing with an electronic
detector:
(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 valves.
(c) Connect a drum of refrigerant-22 to the center hose connection of the charging manifold.
Collect the refrigerant-22 drum so that only gas will be used for pressurization.
(d) Open both unit service valves and the charging manifold valves.
(e) Open the refrigerant drum valve slightly and adjust as necessary to prevent formation of frost, and
allow system pressure to build up until the gages read 4050 psi (2.8 - 3.5 kg/cm2).
(f) Close the charging manifold valves and the refrigerant drum valve.
(g) Remove the refrigerant-22 drum from the center hose connection.
(h) Connect a nitrogen regulator and cylinder of dry nitrogen to the center hose connection.
(i) Open the charging manifold valves and the nitrogen cylinder and regulator valve. Allow system
pressure to buildup until gages read 350 psi (24.7 kg/cm2).
(j) perform leak tests, then discharge and purge the system, in accordance with paragraphs 5-6 and
5-7 before performing maintenance, or before evacuating and charging the system, as appropriate.
(3) Final leak testing. Always perform a final leak test after performing any repair or replacement of
components before the air conditioner is reassembled and the refrigeration system is evacuated and charged.
5-13