TM 9-4120-388-14
Table 4-1. Unit Preventive Maintenance Checks and Services (PMCS) (Cont.)
ITEM TO BE
ITEM
PROCEDURES
lNSPECTED/SERVICED
NO.
e. Turn mode selector switch to VENTILATE. Fan
Operation Checks (cont)
20 (cont)
Should start.
f.
Use a paper streamer or smoke and note amount of
air being discharged from conditioned air outlet grille.
g. Open fresh air damper fully.
h. Close conditioned air intake grille louvers fully.
i.
Again check air flow as in step f above. Air flow should
be approximately the same.
Fully open louvers in conditioned air intake grille and
j.
fully dose fresh air damper.
k. Turn Temperature control thermostat knob to fully
INCREASE (clockwise) position and then turn mode
selector switch to LO HEAT. Place your hand in air
flow from the conditioned air outlet grille and feel for a
temperature rise. When discharge air temperature has
reached a relatively stable level, turn mode selector
switch to HI HEAT and feel for a further temperature
rise. Next turn Temperature control thermostat knob
to fully DECREASE (counterclockwise) position. Feel
that discharge air temperature drops to approximately
same relatively stable level previously noted in LO
HEAT. Finally, turn mode selector switch to LO HEAT
and feel discharge air temperature drop to ambient level.
NOTE
The temperature control thermostat has an effec-
tive functional range between 40F and 90F (5C
and 32C). In extreme conditions when ambient
air temperature is below 40F (5C) or above 90F
(32C), operation in either LO HEAT or HI HEAT
mode will vary from that described above.
Turn Temperature control thermostat knob to fully
l.
INCREASE (clockwise) position, then turn mode selector
switch to COOL. Note that evaporator and condenser
fans start immediately and that compressor starts
approximately 30 seconds later. Hold your hand in air
flow from condensed air outlet grille; there should be no
change in temperature. Now turn Temperature control
thermostat knob to fully DECREASE (counterclockwise)
position and feel outlet air temperature begin to drop
almost immediately. Leave controls in present position
and perform the next check.
m. After 15 minutes of operation check the sight glass and
compare refrigerant condition with the color coded
information plate provided. (See para 2-3.)
n.
Turn mode selector switch to OFF and observe that
all air conditioner functions cease.
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