REFRIGERANT PRESSURE CHECK - TM-9-4120-428-140239

TM 9-4120-428-14

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DIRECT SUPPORT MAINTENANCE

AIR CONDITIONER, HORIZONTAL, COMPACT

(NSN 4120-01-502-1319)

REFRIGERANT PRESSURE CHECK

INITIAL SETUP:

Goggles, WP 0000 00, Item 2

Tools

Gloves, WP 0000 00, Item 2

N/A

Equipment Condition

Materials/Parts

Install service manifold

Refrigeration Unit Service Tool Kit, WP 0000 00, Item

TESTING

1. Check that the unit HIGH and LOW pressure charging valves are open and all four service manifold valves are

closed.

2. Both gages should read the same. Check the reading with the appropriate column in Table 1. If the system is

partially charged, the pressure should be approximately equal to that shown in the table for the appropriate ambient

temperature. If the pressure is considerable less than the reading shown in Table 1, the system does not contain

enough refrigerant to continue the pressure check; proceed directly to leak testing (See WP 0069 00).

3. Turn the air conditioner on and operate in COOL mode with the TEMPERATURE SELECTOR at the fullest cooler

setting for five minutes.

4. Allow gages to stabilize and take readings of the two gages.

If the discharge and suction pressures are at (or near) the same valve, a pressure equalizer solenoid valve L2 or compressor

failure is indicated.

If discharge pressure is low and suction pressure is normal, a low refrigerant is indicated (Table 2).

b) If discharge pressure is normal and the suction pressure ids either high or low, failure or maladjustment of

the pressure regulator valve is indicated (Table 2).

c) If ice forms on the evaporator coil, or evaporator coil does not cool during operation, failure or malfunction

of the evaporator expansion valve is indicated.

d) If the discharge pressure valve is high and suction pressure is normal, a malfunction of quench the valve is

indicated.

e) If the discharge pressure is above 540 psi, the pressure relief valve malfunction is also indicated.

5. When pressure tests are completed, turn the unit off and proceed with any maintenance action indicated.

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