REFRIGERANT PRESSURE CHECK. - TM-5-4120-383-140209

TM5-4120-383-14

5-19.

REFRIGERANT PRESSURE CHECK.-Continued

e. Open high (discharge) pressure service valve sliqhtly

to purge air from hose. Tighten high pressure hose

connection at gage fitting as soon as a hissing sound is

heard.

f. Open low (suction) pressure service valve slightly to

purge air from hose.

Tighten low pressure hose connection

at gage fitting as soon as a hissing sound is heard.

Open low (suction) and high (discharge) charging valves.

h. Both gages should read the same. Check the reading with the

appropriate column in Table 5-2.

If the system is even partially

charged, the pressure should be approximately equal to that shown

in the table for the appropriate ambient temperature.

If the

pressure is considerably less than shown in the table, the system

does not contain enough refrigerant to continue the pressure check;

proceed directly to leak testing.

Turn air conditioner on and operate in COOL mode with

TEMPERATURE SELECTOR in full COOLER setting for a few minutes.

j. With unit operating allow gages to stabilize.

Take readings

of the two gages.

(1) lf discharge and suction pressures are at, or near, the

same value, a pressure equalizer solenoid valve L2 malfunction, or an

internal compressor failure is indicated.

(2) If discharge pressure is low and suction pressure is

normal (see Table 5-3) a low refrigerant charge is indicated.

(3) If discharge pressure is normal and suction pressure is

either high or low, failure or maladjustment of the pressure

regulator valve is indicated.

(4) If ice forms on evaporator coil, or evaporator coil does

not cool, during operation, failure or malfunction of evaporator

expansion valve is indicated.

(5) If discharge pressure is high and suction pressure is

If discharge

normal, a malfunction of quench valve is indicated.

pressure is above 540 psig, pressure relief valve malfunction is

also indicated.

k. When pressure tests are completed, proceed with the

maintenance action indicated.

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