REFRIGERATION SYSTEM TROUBLESHOOTING.

TM5-4120-383-14

5-17.

REFRIGERATION SYSTEM TROUBLESHOOTING.

The two most likely malfunction symptoms to be reported to direct

support maintenance are:

(1) Unsatisfactory color or bubbles

observed in the sight glass; and (2) reduced cooling capacity.

Discussion with operators and/or organizational maintenance

personnel as to how the symptoms appeared can often be more

informative than the symptoms themselves.

Sight Glass Indications. There are two indications that may

be observed in the sight glass; (1) color as a result of moisture

content in the refrigerant, and (2) vapor bubbles in the liquid

refrigerant.

(1) Color Change. 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. A

gradual change from green into chartreuse over an extended period

of time is normally an indication that the dehydrator is becoming

saturated with moisture. A sudden change of color is highly

unlikely unless a rupture occurs allowing all refrigerant to

escape.

(2) Bubbles. The appearance 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 being 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.

NOTE

When the system goes into bypass numerous bubbles

will appear. This is normal. Be sure that the

refrigeration system is under full load when

observing the sight glass for refrigerant condition.

b. Reduction in Cooling Capacity.

A reduction in cooling

capacity will occur as a natural result if refrigerant is lost from

the system; with a total loss of cooling if all refrigerant is

lost.

However, in some conditions a considerable proportion of the

refrigerant may be lost before the reduced cooling capacity is

noticeable. Sudden or erratic 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.

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