TM 9-4120-408-14
1-15. FUNCTIONAL DESCRIPTION. (Continued)
b. The condenser fan draws outside ambient air over and through the condenser coil. The high temperature, high
pressure gas from the compressor is cooled by the flow of air and is changed into a high pressure liquid.
c. The receiver stores excess refrigerant in the system until it is drawn into the evaporator.
e. The liquid indicator indicates the presence of moisture and quantity of refrigerant in the system.
f. The expansion valve controls the amount of liquid refrigerant delivered to the evaporator coil. The expansion
valve senses the temperature and pressure of the refrigerant as it leaves the evaporator coil. By use of a
sensing bulb and " xternal equalizer lines the valve constantly adjusts the flow of liquid refrigerant to the
e
evaporator coil.
g. Liquid refrigerant, leaving the expansion valve, passes through the distributor and enters the evaporator coil. As
the liquid enters the coil at a reduced pressure, the reduction in pressure and the warmer air being forced across
the tubes of the coil cause the refrigerant to boil and change to a gas (vapor). Warm air from the conditioned
space is circulated over and through the evaporator coil by the evaporator blower. Refrigerant absorbs heat as it
converts from liquid to gas. As the air from the conditioned spaces comes in contact with the evaporator coil,
heat is absorbed and the air is cooled.
h. The service valves are provided for charging and general servicing of the refrigerant system.
l. The low pressure and high pressure cut-out switches are provided to protect the unit from damage due to
pressure extremes.
j. The air conditioner is powered by 28VDC, 66 amperes, and is controlled by a 7 position rotary switch. Refer to
diagrams (Figures I-1 through I-3) for details of the electrical system.
1-11