OPERATION.

TM 5-4120-339-14

(f) For cooling with a mixture of recirculated air and fresh air drawn through a chemical biological filter

unit when the outside air is contaminated, close damper door and partially close intake grille damper. (Applicable only if

the air conditioner is equipped with a chemical biological filter unit.)

(2) Heating Operation. (Refer to figures 2-1 and 2-2.)

(a) Position thermostat for desired temperature.

(b) Place fan speed toggle switch in desired position.

(d) For heating with 100 percent recirculated air, close damper door and open intake grille damper.

(e) For heating with a mixture of recirculated air and fresh air, open damper door and partially close

intake grille damper.

(f) For heating with a mixture of recirculated air and fresh air drawn through a chemical biological filter

unit when the outside air is contaminated, close damper door and partially close intake grille damper. (Applicable only if

the air conditioner is equipped with a chemical biological filter unit.)

(3) Ventilating Operation. (Refer to figures 2-1 and 2-2.)

(a) Place the selector switch in "VENTILATE" position.

(b) Place fan speed toggle switch in desired position.

NOTE

If the air conditioner fails to start, pull, then push circuit breaker knob.

Stopping. Turn selector switch to "OFF". (Refer to figure 2-1.)

Section IV. Operation Under Unusual Conditions

2-5.

OPERATION IN EXTREME COLD.

a. The air conditioner is designed to operate on the cooling cycle without forming frost or ice on the evaporator

coil at an ambient (outside) temperature as low as 50F (10C).

b. If cooling air is desired at ambient (outside) temperatures lower than 50F (10C), set the selector switch knob

to "VENTILATE".

Make sure that the electrical system is free of ice and moisture.

2-5