TM 9-4120-401-14
1-8. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS. - continued
CHARGING VALVE, REFRIGERANT SUCTION LINE (LOW PRESSURE) (22). Provides a connection point for
charging and checking suction line pressure.
CONDENSER DISCHARGE AIR LOUVER ASSEMBLY (23). This louver assembly is automatically controlled by
the actuating cylinder, item 43.
CONDENSER FAN AND MOTOR (24). This fan and motor draws outside air over the condenser coil to remove
heat from the refrigerant passing through the tubes of the condenser coil.
CONDENSER COIL (25). Made up of interconnected parallel copper tubes retained in a series of multiple, closely
spaced aluminum fins. This coil serves as a heat exchanger to remove the heat from the compressed refrigerant
vapor so that it will condense into a Iiquid.
RECEIVER (26). The receiver acts as a storage tank for the Iiquid refrigerant.
COMPRESSOR (27). 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 attached to the lower part of
the container. 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 and is thermostatically controlled to prevent overheating.
DEHYDRATOR, DESICCANT, REFRIGERANT (FILTER-DRIER) (28). Removes moisture and contaminants from
the refrigerant.
LOW REFRIGERANT PRESSURE CUTOUT SWITCH (29). This switch is facto set to shut the compressor off if
the refrigerant suction line pressure drops to 2 to 12 psig (0.141 to 0.844 kg/cm2 ).
SOLENOID VALVE, PRESSURE EQUALIZING (30). This valve is normally open when the compressor is NOT
running to equalize the pressure at the suction and discharge sides of the compressor. It closes when the
compressor starts.
RECTIFIER (31). Converts the relay, item 41, load side ac voltage to dc for use by solenoid valve, item 30.
EXPANSION VALVE (32). Meters refrigerant flow to the evaporator during cooling cycles when operating in the
COOL mode.
COIL FROST SWITCH (33). Thermostatic switch that opens compressor circuit if evaporator coil begins to ice.
MIST ELIMINATOR (34). The purpose of the mist eliminator is to trap droplets of condensed water from the
evaporator, so that they will not be blown into the air conditioned space.
HEATING ELEMENTS (35). Consists of two banks of heating elements that warm the air fmm the conditioned
space as needed.
EVAPORATOR COIL (36). Similar in construction to the multiple tube, finned condenser coil. This coil serves as a
heat exchanger for the refrigerant to absorb heat from the room or enclosure air circulated through the evaporator
section.
LOGIC BOX ASSEMBLY (37). Electronic device that monitors unit sensors and control settings to operate the
unit and drive status (fault Iights).
MOTOR CONTROLLER (38). Electronic device that conditions and regulates motor and heater supply power
according to signals sent from logic box assembly, item 37.
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