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TM 5-4120-287-15
(4) 28V DC Supply 3/4 amp fuse indi
cator and fuse holder. This indicator lamp
lights when the 28-volt dc supply line over-
loads and blows the 28-volt dc fuse.
c. Monitoring Instruments. The liquid re-
frigerant sight indicator and moisture indica-
tor, and the evaporator and condenser section
filter clean indicators, continuously monitor
the air conditioner air circulation system and
vapor cycle system. The daily and quarterly
prevefrtive maintenance services (pama 3-6 and
3-7) must be performed as indicated by the
monitoring instrument readings for the air
conditioner to ’operate at its rated capacities.
(1) Refrigerant liquid line sight glass and
moisture indicator. The refrigerant liquid
sight indicator (fig. 2-4) flush mounted be-
neath the evaporator rear access panel, allows
visual observation of the refrigerant-12 flow.
Bubbles, or a milky appearance in the sight
glass indicate a shortage of refrigerant or a
restricted liquid line. The moisture indicator,
located within the refrigerant liquid sight in-
dicator, indicates moisture level in the vapor
cycle system by changing color from green to
Figure2-4. Refrigerant liquid sight indicator and evaporator filter clean indicator.
yellow. Notify field maintenance should the
moisture indicator turn yellow, or bubbles ap-
pear in the sight glass.
(2) Evaporator filter clean indicator. The
evaporator filter clean indicator (fig. 2-4)
flush mounted beneath the evaporator rear ac-
cess panel, monitors the velocity of air passing
through the evaporator filter screen. When the
indicating ball rises to the upper arrows (fig.
2-4) service the evaporator inlet filter (para
3-11).
(3) Condenser filter clean indicator. The
condenser filter clean indicator (fig. 2-5.)
flush mounted on the air conditioner rightside
panel, monitors the velocity of air passing
through the condenser filter screen. When the
indicating ball rises to the upper arrows (fig.
2-5.) service the condenser air inlet filter
(para 3-10).
FIGURE 2-5. Condenser filter clean indicator.
2-7
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