Section III. GENERAL MAINTENANCE INSTRUCTIONS

TM 5-4120-352-14

Section III. GENERAL MAINTENANCE INSTRUCTIONS

5-10. Shims.

5-6. General.

Be sure to remove all shims where used. Keep

This section contains general repair in-

shims together and identify them as to location.

structions which would otherwise have to be re-

peated several times.

5-11. Repairing Damaged Threads.

Damaged threads should be repaired by use of a

5-7. Refrigeration System.

thread restorer or by chasing in a lathe. Internal

a. Opening System. When the refrigeration

threads should be repaired with a tap of the correct

system must undergo maintenance that requires

size. If threads cannot be satisfactorily repaired, re-

the system to be opened for removal of parts, the

place the part,

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)

5-12. Repair of Damaged Machined

and tested for leaks.

a n d Polished Surfaces.

b. Removal of parts. It may be necessary to

Smooth rough spots, scores, burrs, galling, and

remove some tubing and fittings along with a part

gouges from damaged machined and polished sur-

that is to be replaced. The tubing and fittings can

faces so that part will efficiently perform its normal

then be removed from the defective part and in-

function. The finish of the repaired part is to ap-

stalled in the new part. Care should be exercised in

proximately that of the original finish. In per-

opening joints or resoldering to prevent damage to

forming any of these operations, critical dimensions

other parts of the air conditioner.

must not be altered.

c. Brazing. Braze copper-to-copper joints with

silver solder type 3, 4 or 6A specification QQ-S-561

5-13. Removal of Rust or Corrosion.

and copper-to-brass or copper-to-steel with type 4 or

Remove corrosion from all parts of material. To

6A specification QQ-S-561 per MIL-B-7883. Solder

remove rust or corrosion, use wire brush, abrasive

melting point is 1160F (625C). All brazed or sol-

cloth, sand blast, vapor blast equipment, or rust re-

dered joints shall be made with an atmosphere of

mover except on highly polished surfaces. On these

inert gas to prevent internal oxidation.

surfaces, buffing or the use of the use of crocus cloth

is recommended.

5-8. Insulation and Gaskets.

Replace damaged insulation and gaskets. Ce-

5-14. Tubes and Fittings.

ment loose insulation.

Check tubes and fittings for cracked or split

condition. Check tubing for kinks. Replace defective

5-9. Hardware.

fittings. Replace damaged tubing with tubing of

Replace any damaged screw, washers, lock

same size. Take care in making bends in tubing to

washers or nuts. Use screws of correct length to

prevent kinking of tubing. All tubing and fittings

hold parts securely, In some applications screws

must be completely clean on inside prior to

that are too long may hit bottom before the head is

installation.

tight against part it is to hold or may cause damage

to the threads or other parts.

5-15. Valves.

Valves and other parts should be handled care-

fully to prevent damage. Capillary tubes must be

handled very carefully to prevent kinking of the

tubes.

5-6