TM9-4120-400-14
BRAZING/DEBRAZING PROCEDURES. - continued
5-12.
Never use a heating torch on any part that contains refrigerant. Heat causes the
refrigerant to break down and form carbonyl chloride (phosgene), a highly toxic and
corrosive gas. All refrigerant must be discharged from the system and the entire system
must be purged with dry nitrogen before beginning any debrazing operation.
NOTE
It may be easier to access a component by cutting or debrazing the copper lines in
accessible areas and removing part of the interconnecting tubing with the component.
3. If debrazing a joint on a valve, disassemble the valve to the extent possible and wrap all but the joint with a wet
cloth to act as a heat sink.
4. 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 is separated.
CLEANING
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 wire brush. Be sure no filler alloy or other debris is left inside
any tubing, fitting, or component.
BRAZING
1. 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). (See para 5-11.)
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.
2. Protect insulation, wiring harnesses, and other components with appropriate shields.
5-31