Section III TECHNICAL PRINCIPLES OF OPERATION
1-11. REFRIGERATION CYCLE See figure 1-3.
Figure 1-3. Refrigeration Schematic
a. Cooling Cycle - When the MODE SELECTOR SWITCH and the TEMPERATURE CONTROL are set for
COOLER the following takes place:
· The compressor (1) takes cold, low pressure refrigerant gas and compresses it to a high temperature, high
pressure gas. This gas flows through the metal tubing to the condenser coil (2) and receiver (3).
· The condenser fan draws outside ambient air over and through the condenser coil (2). The high temperature,
high pressure gas from the compressor (1) is cooled by the flow of air and is changed into a high pressure liquid.
· The refrigerant desiccant dehydrator (filter drier) (4) removes any moisture (water vapor) or dirt that may be
carried by the liquid refrigerant.
The liquid indicator (sight glass) (5) indicates the presence of moisture and quantity of refrigerant in the
· The solenoid valve (9) is controlled by the temperature selector on the control panel. This valve will shut off
the flow of refrigerant to the evaporator section when the temperature in the conditioned area reaches the set point.
· The expansion valve (6) controls the amount and pressure of liquid refrigerant to the evaporator coil (8). The
expansion valve (6) senses the temperature and pressure of the refrigerant as it leaves the evaporator coil. By use of a
sensing bulb and "external equalizer line" the valve constantly adjusts the flow of liquid refrigerant to the evaporator coil
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