Manual
14
FRCC.ES.014.A6.22
Sequence of operation – Field wiring
Sequence of operation
Refrigeration Cycle
1. Defrost timer is powered by the condensing
unit, connecting the supply to terminal “1” and
“N”.
2. The fan delay and the defrost termination
thermostat is closed in the fan delay position
and open in the defrost termination position.
The evaporator fan(s) run continuously.
3. The defrost heaters are off during refrigeration
cycle.
4. The room thermostat closes when the
temperature rises above the desired setting.
5. The liquid line solenoid valve(LSV) gets
energized and opens to allow the liquid
refrigerant to flow through the evaporator.
6. The low-pressure control switch closes when the
suction pressure rises above the cut-in setting.
7. The compressor contactor gets energized and
supply power to allow the compressor and
condenser fan to run.
8. The room temperature gradually decreases to
the desired temperature.
9. Once the desired temperature is attained, the
thermostat opens and the liquid line solenoid
closes, it will in turn stop the refrigerant flow
through the evaporator.
10. Suction pressure decreases and the
compressor contactor opens when the
pressure drops below the cut-out setting on
the low-pressure control. The compressor and
condenser fan stop running.
11. This cycle is repeated as many times as
necessary to satisfy the room thermostat.
12. Frost may form on the evaporator coil until the
defrost cycle is initiated.
