REFRIGERATION SYSTEM TROUBLESHOOTING

TM 9-4120-428-14

0072 00

DIRECT SUPPORT MAINTENANCE

AIR CONDITIONER, HORIZONTAL, COMPACT

(NSN 4120-01-502-1319)

REFRIGERATION SYSTEM TROUBLESHOOTING

INITIAL SETUP:

Equipment Condition

Unit operating in full COOL mode.

EXAMINATION

1. Check the sight glass condition.

A bright green color indicates that the refrigerant is dry. As moisture content increases, the color will

gradually change from chartreuse until it reaches pure yellow. On average, a gradual change from green to

chartreuse over an extended period of time is an indication that the dehydrator is becoming saturated with

moisture. A sudden change of color is highly unlikely, unless a rupture occurs, allowing the refrigerant to

escape. Correct as indicated.

NOTE

Numerous bubbles will appear when the system goes into bypass. This is normal. Be sure

that the refrigeration system is under full load when observing the sight glass for

refrigerant condition.

b) The experience of an occasional bubble in the sight glass can be expected, especially when operating in a

high ambient temperature. A gradual increase in the number and frequency of bubbles is usually an

indication that the refrigerant charge is lost from the system through a small leak. The number and

frequency of bubbles will also increase if the refrigeration system becomes overheated. The sudden

appearance of numerous bubbles is usually an indication of a serious leak. Correct as indicated.

2. Check for decreased cooling capacity.

A reduction in cooling capacity will occur as a natural result if the refrigerant escapes from the system. This will result in a

total loss of cooling if all refrigerant is lost. In some conditions, however, a considerable portion of the refrigerant may be

lost before the reduced cooling capacity is noticeable. Sudden reduction or complete loss of cooling capacity is often caused

by the malfunction of one of the valves in the refrigeration system. Cooling capacity will also be reduced if the refrigeration

system becomes overheated. Correct as indicated.

NOTE

FOLLOW-ON MAINTENANCE:

Turn unit OFF

END OF WORK PACKAGE

0072 00-1