|
| |
TM 9-4120-389-14
When the temperature control thermostat on the control panel senses that cooling conditions have
reached the set point, it closes the liquid line solenoid valve (10) to shut off refrigerant flow to the evaporator
coil (14).
As the compressor suction pressure starts to drop, the pressure regulating valve (16) opens to allow
hot gas from the compressor to bypass the condenser (5) and evaporator (14).
The expansion valve (quench) (17) senses the temperature of the gas at the suction side of the
compressor. To prevent excessively hot gas from reaching the compressor, the expansion valve (quench) (17)
opens to allow liquid refrigerant to mix with the hot gas.
The cylinder assembly (15) actuates condenser damper which modulates the air flow across the
condenser coil (5). During the hot gas bypass mode, the condenser damper closes, restricting airflow through
the condenser coil (5). This action results in a condition whereby a minimum discharge pressure is maintained
at the compressor.
The charging valve (4) is provided for charging, and general servicing of the high and low pressure
sides of the refrigerant system.
The pressure switch (low) (2), the pressure switch (high) (6), and the fusible (7) are provided to
protect the unit from damage due to pressure extremes.
1-11. HEATING.
a. HI HEAT mode. When the mode selector switch is set for HI HEAT the six heating elements, located
behind the evaporator coil, are energized. These elements are protected from overheating by a thermal cutout
switch. Three of the elements are thermostatically controlled by the temperature control thermostat, and the
remaining three are on all of the time.
b. LO HEAT mode. When the mode selector switch is set for LO HEAT, only the three thermostatically
controlled elements are used.
1-9/1-10 blank
|
