Figure 2-2. Visual Indicators

TM 5-4120-359-14

2-3. INDICATORS

a. The run indicator light (fig. 2-1), the time totalizing meter, and the refrigerant sight glass are the only visual

indicators incorporated in the Air Conditioners.

Figure 2-2. Visual Indicators

(1) The time totalizing meter is used to determine maintenance intervals.

(2) The sight glass is a port window through which the refrigerant condition can be seen. Liquid refrigerant

actually flows through the sight glass chamber only during cooling cycles when the air conditioner is in operation in the

COOL mode. 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 becomes

unacceptable. Excessive moisture in the refrigerant may damage or possibly destroy the compressor. If the liquid

refrigerant observed in the sight glass has an opaque, milky appearance, or frequent bubbles appear, the volume of

refrigerant is low and the system should b charged. Either moisture or low charge indications should be reported to direct

support maintenance.

CAUTION

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.

Change 6 2-3