Electrical, Refrigeration and
µ
P-D Menu Flow Diagrams
Refrigeration Schematic: Modulation Cool
9-39
CSR-20 & CSR-40, September 1999
Flow and Pressure Diagram
CSR-20 & CSR-40
Modulation Cool
7.
Warm Gas Bypass Valve
Is a normally CLOSED solenoid.
It OPENS when energized to reduce cooling capacity when the tem-
perature is close to setpoint.
16. Modulation Valve (MV)
Is a normally OPEN valve.
It CLOSES when energized. As the signal strength is increased, the
valve closes more. The controller regulates the signal to the valve
based on sensor temperatures and power limit requirements.
18. Liquid Injection Valve (LIV)
Is a normally CLOSED valve.
It OPENS when energized. When liquid injection is required, the
valve is pulsed open and closed on a 10 second cycle.
The valve is energized when the compressor head temperature is above
138 C (280 F) or when the modulation valve closes more than 45%.
19. Electric Heaters
During the DEFROST mode, the electric heaters are pulsed ON and
OFF. The compressor does not operate. The condenser fan and
evaporator fans remain OFF.
During the HEAT mode, the electric heaters are pulsed ON and OFF.
The compressor does not operate. The condenser fan is OFF. The
evaporator fans continue to operate (evaporator fan speed is deter-
mined by return air temperature and economy mode setting).
High pressure gas
High pressure liquid
Low pressure gas
Low pressure liquid
Condensing high pressure gas
Low pressure vaporizing liquid
Liquid refrigerant injection
Modulated pressure
High pressure gas injection
High pressure gas injection
