TM 9-4120-399-14
Section VI. UNIT MAINTENANCE PROCEDURES.
for the Unit maintenance as defined in the Maintenance Allocation Chart located in Appendix B.
Before performing any procedure in this section, use the Unit Troubleshooting procedures to
identify and locate the parts on the air conditioner unit requiring maintenance.
wires, terminals, connectors, etc., rather than splicing wires, bending ends to form terminals, and
other make-shift procedures; although the latter may be appropriate for emergency field repairs.
Determine the proper size and length of wire, or the terminal, or connector to be used for
replacement by referring to Table 4-4, Wire List, and to the wiring diagram.
are soldered; solder alone does not provide sufficient strength to prevent breakage. Joining
surfaces of connections to be soldered must be clean and bright. If a separate flux is used, it
should conform to soldering flux (Appendix E, item 6) and should be brushed onto the joint
before soldering. If an uncored solder is used, it should be a lead-tin solder, (Appendix E, item
1). Wires should always be heated to the point at which the solder will melt completely and
flow into all parts of the joint. Excessive build-up solder "gobs" on the joint should be avoided
or removed.
b. Insulation Joints. The preferred method of insulating electrical joints is by the use of
heat-shrink tubing. To apply, cut a piece of heat-shrink tubing of suitable diameter to a one-
inch length for covering joints at terminals or connectors, or to a length about 1/2 inch (1.3 cm)
longer than the joint to be insulated, and slide the tubing over the wire before making the joint.
After the joint is made, slide the tubing so that it covers the joint, and shrink in place with
moderate heat.
c. Splicing Wires. To repair broken or cut wires that are otherwise sound, the mating ends
can be stripped and spliced. A commercial butt splice can be crimped onto the end to join them,
or a : Western Union wire splice can be made. The latter is made by stripping 1/4 - 1/2 inch
(0.6 - 1.3 c, ) of insulation from the wire ends, holding the ends parallel and facing opposite
directions, then twisting each end around the other wire at least three turns. Solder and apply
insulation as described above.
d. Crimping Terminals. To install a terminal on the end of a wire, strip 1/4 - 1/2 inch (0.6
- 1.3 cm) of insulation from the end of the wire, apply a one-inch piece of heat-shrink tubing
(if the terminals are of the uninsulated type), and insert wire end into the shank of the terminal.
Crimp the shank, and install heat-shrink tubing, if necessary.
