OPERATIONAL CHECKS

TM5-4120-383-14

2-6.

OPERATIONAL

CHECKS.-Continued

If a knocking or pounding noise is heard when the

compressor starts in the following check, immediately

turn the MODE SELECTOR out of the COOL position.

Leave input power connected and wait at least two

hours before attempting another start in COOL mode.

k. Turn the TEMPERATURE SELECTOR control knob to the fully

WARMER (clockwise) position, then turn the MODE SELECTOR switch to

Note that the evaporator and condenser fans start

COOL.

immediately and that the compressor starts approximately 30 seconds

later. Hold your hand in the airflow from the conditioned air

supply louver: there should be no change in temperature. Now turn

the TEMPERATURE SELECTOR control knob to the fully COOLER

(counterclockwise] position and feel the supply air temperature

begin to drop almost immediately. Leave controls in the present

position and perform the next check.

l. After 15 minutes of operation check the sight glass to

determine the refrigerant condition. The sight glass is equipped

with a center indicator that is moisture sensitive. Dry

refrigerant is indicated by green, it turns to chartreuse when the

moisture content becomes undesirable and to yellow when the level

Excessive moisture in the refrigerant may

becomes unacceptable.

If the liquid

damage or possibly destroy the compressor.

refrigerant observed in the sight glass has a milky appearance or

frequent bubbles appear, the volume of refrigerant is low and the

Either moisture or low charge

system should be charged.

indications should be reported to direct support maintenance for

appropriate refrigeration system action.

Do not operate the air conditioner in the COOL mode

if the refrigerant color has reached the yellow band

or if numerous bubbles appear in the sight glass.

COOL mode operation may be continued with the

refrigerant color in the chartreuse band or with only

an occasional bubble appearing in the window, but the

sight glass should be rechecked after each four hours

of operation to insure that the condition has not

become worse.

Observe that all air

m. Turn the MODE SELECTOR switch to OFF.

conditioner functions cease.

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