HIGH HEAD PRESSURE

TM 5-4120-369-14

Troubleshooting - Continued.

Table 5-1.

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

8. HIGH SUCTION PRESSURE (See Table 6-1)

Check for indications of defective thermal expansion valve.

Step 1.

Replace valve (paragraph 5-28).

Step 2.

Check for indications of defective quench valve.

Replace valve (paragraph 5-29).

9. HIGH HEAD PRESSURE (See Table 6-1)

Step 1.

Check to see if condenser coil is dirty.

Clean Coil.

Step 2.

Check for indications of refrigerant overcharge icing of components.

Discharge refrigerant (fig. 6-1) while observing head pressure and sight glass.

Step 3.

Inspect or test condenser fan motor for defective operation.

Repair motor (paragraph 6-8).

Step 4.

Inspect condenser louvers and actuating mechanism for correct adjustment

and proper operation.

Adjust and clean as necessary.

Replace inoperative cmnponents

(paragraph 5-20).

Step 5.

Check for indications of defective quench valve.

Replace defective valve (paragraph 5-29).

Step 6.

Check to see if the compressor is defective.

Replace defective compressor (paragraph 5-16).

DIRECT SUPPORT MAINTENANCE INSTRUCTIONS

Section III.

5-5.

GENERAL.

This section contains general servicing instructions that otherwise would have to be repeated

several times in this manual.

5-6.

TESTING FOR LEAKS .

The air conditioner can be tested for refrigerant leaks by the use of an electronic leak

detector, by the halide teat or by the soap bubble method. The preferred method is use of

the electronic leak detector. If sufficient pressure is not present in the system to accomplish

an adequate leak test, add dry nitrogen at the receiver charging valve to increase the system

pressure to 200 psig, then conduct the leak test. If the system is totally discharged, to con-

serve leak test refrigerant, pressurise the system with R-22 to 72 psig, isolate the compressor

by front-seating the service valves (1 and 2, figure 3-2). At the receiver charging valve

pressurize the system with dry nitrogen to 300 psig, them conduct the leak test.

5-5