Unit Description
30
Purge Mode
Purge Mode is similar to Condenser Evacuation
Mode in previous systems. It is used to move the
refrigerant out of the condenser into the
accumulator when the unit shifts from Cool (or
Null) to Heat. The unit goes into Purge Mode for
20 to 100 seconds before shifting to Heat. The
ambient and return air temperatures determine the
duration. Lower temperatures cause the unit to
stay in Purge Mode longer.
High pressure refrigerant vapor leaves the
compressor and flows through the open CIS to the
condenser. The PV is open so most of the
refrigerant flows from the condenser through the
PV and the purge check valve to the accumulator.
Some of the refrigerant flows through the
condenser check valve, receiver tank, drier, heat
exchanger, expansion valve, and evaporator to the
accumulator. From the accumulator the refrigerant
returns to the compressor through the SPR.
Solenoid and Check Valves
1. Condenser Inlet Solenoid (CIS)-Open/
De-energized
2. Condenser Check Valve-Open
3. Receiver Tank Pressure Check Valve-Closed
4. Purge Valve (PV)-Open/Energized
5. Purge Check Valve-Open
6. Hot Gas Solenoid (HGS)-Closed/
De-energized
Figure 8: Purge Mode
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