Figure 2-1. Controls and Instruments (Sheet 1 of 2)

TM 5-4120-369-14

Controls and Instruments (Sheet 1 of 2)

Figure 2-1.

(4) Low Heat. In the low heat mode, the evaporator fan motor operates continuously and

three of the six heater elements cycle on and off under thermostatic control of the temperature

selector switch. This mode will produce half of the unit's heating capability. Ventilation air will

be drawn into the unit if the vent damper door is open.

(5) High Heat. In the high heat

mode, the evaporator fan motor operates continu-

ously and all six of the heater elements are

activated, but only three of the heater elements will

cycle on and off under thermostatic control

of the temperature selector switch. This mode will

produce maximum heating capability of the

unit. Ventilation air will be drawn into the unit if

the vent damper door is open.

Evaporator Fan Speed Switch. The evaporator fan speed switch has two positions, "low"

and "high." The positions are manually selected to control the evaporator fan speed in all

operating modes. Normally the "low" speed should be selected as it is quieter and requires less

electrical power; however, the "high" speed position has three advantages over "low" which may

dictate its selection:

(1) Maximum cooling capacity can only be achieved in "high."

(2) The increased flow of evaporator air improves sir distribution in the conditioned

space.

(3) Twice as much ventilation air is drawn into the unit in "high."

2-2