TM 9-4120-371-14
TABLE 4-1. UNIT PREVENTIVE MAINTENANCE
CHECKS AND SERVICES (PMCS) (cont.)
Item
Item To Be
Procedures
No.
Inspected/Serviced
23
Operation Checks
a. Be sure the mode selector switch is in the OFF position
and reconnect input power.
Do not check operation in COOL mode until after
input power has been reconnected for a sufficient time
to eliminate any danger of liquid refrigerant
extremely cold conditions, if input power has been
disconnected for a period of less than six hours, an
equal warm-up period should be allowed. If the
disconnected period has been more than
six hours, a full six hour warm-up period is necessary
b. Check that the fabric cover is rolled up and secured.
c. Adjust conditioned air intake and outlet louvers to the full open
position.
d. Adjust fresh air damper to full closed position.
e. Turn mode selector switch to VENTILATE. Fan 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. Airflow should be
approximately the same.
j. Fully open louvers in conditioned air intake grille and fully
close 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 (counter clockwise)
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.
4-41