GENERAL DESCRIPTION
39
SINGLE STAGE CONTROL SYSTEM
(Refer to Refrigeration Diagram in Drawing Section).
Mode: Normal cooling/heating
When there is a call for cooling, the R-404A Liquid Line Solenoid (101-SOL), and the liquid injection
solenoid (108-SOL) energize. The R-404A compressor turns on. The high pressure switch (101-PS) will
turn off the compressor if a high discharge pressure event is reached. Contact Cincinnati Sub-Zero’s
service department if this occurs. The high-pressure switch will automatically reset. When there is call
for cooling, 101-SOL is energized. When the chamber is near the set point, the controller begins to cycle
101-SOL on and off. At the same time, the R-404A hot gas bypass solenoid 109-SOL is cycling on and off
opposite of 101-SOL. If the chamber does not call for cooling for ninety seconds, the refrigeration
system will turn off.
When there is a call for heating, 101-SOL will de-energize and the heaters will energize.
Mode: Humidity
In humidity mode, the system starts in the same manner as above with the following differences:
When dehumidification is called for, the wet coil solenoid valve H111-SOL is energized. This allows
refrigerant to flow to the dehumidification evaporator (item H125).
When humidity is called for, the wet coil solenoid valve H111-SOL is de-energized.
For Dry Bulb Temperature cooling in humidity mode, the liquid line solenoid valve (101-SOL) is
energized. This allows refrigerant to flow through the R-410A dry bulb thermostatic expansion to
reduce the temperature of the chamber.
For Dry Bulb Temperature heating, the liquid line solenoid valve (101-SOL) is deenergized, and the
heaters are energized.
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