TM 9-4120-402-14
1-8. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS. - continued
CONDITIONED AIR DISCHARGE GRILLE (4). Adjustable louvers provide directional control of conditioned air.
RETURN AIR FILTER (5). Filters room or enclosure air as it is recirculated.
INTAKE (RETURN) AIR GRILLE (6). Adjustable louvers allow control of outside (fresh) and return (from room or
enclosure) air.
CONTROL PANEL ASSEMBLY (7). Contains switches, controls and indicators for operating the air conditioner.
See items 8, 9 and 10 for a description of these switches controls and indicators.
ROTARY SWITCH (MODE SELECTOR) (8). Allows selection of unit operating mode.
POTENTIOMETER (TEMPERATURE CONTROL) (9). This control allows adjustment of the conditioned air temperature
while operating in the cool or heat modes.
LIGHT EMITTING DIODES (FAULT LIGHTS) (10). Help to indicate problem areas if the unit fails.
CONTROL ASSEMBLY (11). Contains motor controller, logic box assembly, control voltage transformer, rectifier and
control relays.
EVAPORATOR COIL (12). Multiple tube, finned coil. The coil allows the refrigerant to absorb heat from the room or
enclosure air circulating through the unit.
FABRIC COVER (13). Protects back or exposed side of the unit during periods of shut down. Must be rolled up when
operating in the cool mode or when fresh (outside) air is being used in any mode.
FRESH AIR FILTER AND DAMPER (14). Screens, filters and controls fresh air entering the unit.
REFRIGERANT SIGHT GLASS (15). Visually indicates the condition of the refrigerant flowing in the refrigerant liquid
line during cooling cycles when operating in the COOL mode.
HIGH AND LOW REFRIGERANT PRESSURE CUTOUT SWITCHES (16). The switches are factory set to shut the
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compressor off if the refrigerant discharge line pressure rises to 470 to 490 psig (33.05 to 34.45 kg/cm ) or the refrigerant
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suction line pressure drops to 2 to 12 psig (0.141 to 0.844 kg/cm ).
CIRCUIT BREAKER (17). Located in the main electric line after the EMI filter. Provides circuit protection for the unit.
CONDENSER AIR OUTLET GRILLE (18). Protects personnel from injury and fan from damage.
INPUT POWER RECEPTACLE (19). Connection point for main input power cable.
COMPRESSOR (20). Consists of a reciprocating compressor driven by an electrical motor, hermetically sealed inside a
steel container with a lifetime charge of oil. An external (crankcase) heater is wrapped around the lower part of the
container on the Carrier compressor and inserted into a well at the lower part of the container on the Keco compressor.
The purpose of the heater is to prevent possible damage to the compressor caused by liquid refrigerant accumulation in
the crankcase during a period of shut down. The heater is connected directly to input power after the circuit breaker and
is thermostatically controlled to prevent overheating.
CONDENSATE WATER DRIP PAN AND DRAIN TRAP (21). The drip pan is located directly below the evaporator coil
and mist eliminator and is built into the casing. Its purpose is to collect condensate that drips off the evaporator coil and
mist eliminator during cooling operations. Condensate water then flows through a drain tube to the drain trap located
inside the lower left front corner of the cabinet. The drain trap contains a check valve that prevents air flow between the
condenser and evaporator sections through the drain tube.
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