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para 5-29
para 5-28
para 5-31
para 6-3
para 6-8
para 5-20
para 5-17
para 5-29
Malfunction
.—
Table 5-1. Troubleshooting-Continued
Probable Cause
I
Corrective
Action
I
Section III.
GENERAL MAINTENANCE INSTRUCTIONS
5-6. General
This section contains general repair instructions
which would otherwise have to be repeated several
times.
5-7. Refrigeration S y s t em
a. Opening System.
When the refrigeration
system must undergo maintenance that requires the
system to be opened for removal of parts, the
system must first be discharged and purged (para
6-3). After the repair has been made and all
soldering completed, the system must be charged
(para 6-3) and tested for leaks.
b. Removal of Parts. It may be necessary to
remove some tubing and fittings with a part that is
to be replaced. The tubing and fittings can then be
removed from the defective part and installed in the
new part. Care should be exercised in opening
joints or resoldering to prevent damage to other
parts of the air conditioner.
c. Brazing. Braze copper to copper joints with
silver solder type 3, 4 or 6A specification QQ-S-561
and copper to brass or copper to steel with type 4 or
6A specification QQ-S-561 per MIL-B-7883.
Solder melting point is 1160°F. All brazed or
soldered joints shall be made with an atmosphere of
inert gas to prevent internal oxidation.
5-8. Insulation and Gaskets
Replace damaged insulation and gaskets. Cement
loose insulation.
5-9. Hardware
Replace any
damaged screws, washers, lock
washers or nuts. Use screws of correct length to
hold parts securely. In some applications screws
that are too long may hit bottom before the head is
tight against part it is to hold or may cause damage
to the threads or other parts.
5-10. S h i ms
Be sure to remove all shims where used. Keep
shims together and identify them as to location.
5-11. Repairing Damaged Threads
Damaged threads should be repaired by use of a
thread restorer or by chasing in a lathe. Internal
threads should be repaired with a used tap of the
correct size.
If threads cannot be satisfactorily
repaired, replace the part.
5 - 1 2 . R e p a i r o f D a m a g e d M a c h i n e d a n d
Polished Surfaces
Smooth rough spots,
scores, burs, galling, and
gouges from
damaged machined and polished
surfaces so that part will efficiently perform its
normal function. The finish of the repaired part is
to approximate that of the original finish. In
performing any of these operations, critical
dimensions must not be altered.
5-13. Removal of Rust or Corrosion
Remove corrosion from all parts of material. To
remove rust or corrosion, use wire brush, abrasive
cloth, sand blast, vapor blast equipment, or rust
remover except on highly polished surfaces. O n
these surfaces. buffing or the use of crocus cloth is
recommended.
5-14. Tubes and Fittings
Check tubes and fittings for cracked or split
condition. Check tubing for kinks. Replace
defective fittings. Replace damaged tubing with
tubing of same size. Take care in making bends in
tubing to prevent kinking of tubing. All tubing and
5-4
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