Leak Testing - TM-5-4120-347-140128

TM5-4120-347-14

(2) Before debrazing a joint on a valve, disassemble the valve to the extent possible, then wrap all but the

joint with a wet cloth to act as a heat sink.

The polyurethane foam used as insulation in the air conditioner will break down to form toxic gases

if exposed to the flame of a torch or brazing temperature.

(3) Protect insulation, wiring harnesses, and other surrounding components with appropriate shields.

(4) Be sure the work area is well ventilated and that dry nitrogen is flowing through the refrigeration

system at a rate of 1 -2 cfm (0.028-0.057 ins/minute).

(5) Apply sufficient heat uniformly around the joint to quickly melt the filler alloy. If heat is applied slowly,

or only on one side, the entire component or length of tubing will be heated and filler alloy in adjacent joints

may also be melted. Remove heat as soon as the joint separates.

d. Cleaning Debrazed Joints. All filler alloy must be cleaned from debrazed joints before reassembly. Heat

each piece of the joint until the filler alloy is melted and then wipe it away with a fiber-glass cloth. Be sure no

filler alloy or other debris is left inside any tubing, fitting or component.

e. Reassembly. If tubing sections or fittings were removed with a component, debraze them from the

component, clean the joints, and braze them to the new component before reinstallation.

f. Brazing. Braze joints within the air conditioner as follows:

(1) Position the component to be installed.

(2) To prepare for brazing a joint on a valve, disassemble the valve to the extent possible, then wrap all

but the joint with a wet cloth to act as a heat sink.

(3) Protect insulation, wiring harnesses, and surrounding components with appropriate shields.

(4) Be sure the work area is well ventilated and that dry nitrogen is flowing through the refrigeration

system at a rate of 1 -2 cfm (0.028 -0.057 m3/minute).

(5) Apply sufficient heat uniformly around the joint to quickly raise it to a temperature that will melt the

filler alloy. Remove heat as soon as brazing is completed.

The entire refrigeration system 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.

a. Access.

NOTE

The following steps cover all the disassembly actions necessary to prepare a system for complete

leak testing. If the air conditioner has been partially disassembled for repair, most of these actions

will already have been accomplished.

(1) Disconnect power at power source.

(2) Remove the top covers. (See paragraph 4-18.)

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