DESCRIPTION AND USE OF CONTROLS AND INDICATORS

TM 9-4120-425-14&P

DESCRIPTION AND USE OF CONTROLS AND INDICATORS

GENERAL

The air conditioner is a self-contained and electric powered unit that provides 36,000 BTU/HR for cooling or 31,200

BTU/HR for heating. Once started, it operates automatically due to the relationship of the components, controls and

instruments.

The air conditioner is designed for a variety of installations and for operation under a wide range of climactic conditions.

It is also designed for continuous or intermittent operation as a self-contained unit. Operators must be aware of any

peculiarities or operational limitations for their specific installation. See the appropriate shelter or system manual for

instructions peculiar to your specific installation.

The air conditioner is not equipped with a CBR filter, however, the unit could be connected to external filtering

equipment for operation under CBR environmental conditions.

OPERATOR'S CONTROLS

1. Cooling

With the MODE SELECTOR switch in COOL position, the fan motor is energized. The fan motor runs continuously.

The temperature selector switch determines the cooling mode of unit. With the temperature selector switch calling for

compressor operation, the liquid line solenoid valve opens and closes with the electronic thermostat switch to control the

flow within the refrigerant circuit. The air conditioner is protected from current overload by a circuit breaker in the

control module and a thermal overload in the compressor terminal cover.

2. Heating

With the MODE SELECTOR switch in the HEAT position, air is blown by the evaporator fan as in cooling, but the

heating elements are energized instead of the refrigeration system.

3. Ventilation

Placing the MODE SELECTOR switch in the VENT position energizes the evaporator fan motor which forces air out of

the evaporator discharge louver into the room. The amount of outdoor air used for ventilation is determined by the

position of the ventilation damper door.

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