Table 4-1. UNIT PREVENTIVE MAINTENANCE CHECKS AND SERVICES (PMCS) QUARTERLY SCHEDULE (cont)

TM 5-4120-393-14

Table 4-1. UNIT PREVENTIVE MAINTENANCE CHECKS AND SERVICES (PMCS) QUARTERLY SCHEDULE (cont)

Item

Item To Be

No.

Inspected/Serviced

Procedures

Turn mode selector switch to VENTILATE. Evaporator

fan should start.

Use a paper streamer or smoke and note amount of air

being discharged from conditioned air outlet grille.

Open fresh air damper fully.

Close conditioned air intake grille louvers fully.

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

fully close fresh air damper.

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

at the center of 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 effective functional range between 40 F

and 90 F (5 C and 32 C).

In extreme

conditions when ambient air temperature

is below 40 F (5 C) or above 90 F (32 C),

operation in either LO HEAT or HI HEAT

mode will vary from that described above.

4-33