Thermo King T-500R Maintenance Manual page 52

Heat/Defrost Mode
T-Series (except T-500R/T-Dairy)
The refrigerant flow in Heat/Defrost Mode is a conventional hot gas heat cycle. The CIS is closed and the HGS is open so high
pressure refrigerant vapor leaves the compressor and flows through the HGS to the hot has line. Most of the refrigerant flows
through the hot gas line and the drain pan heater to the evaporator. There, the refrigerant heats the evaporator and returns to the
compressor through the heat exchanger, accumulator, and ETV. Some of the refrigerant flows through the receiver tank pressure
check valve and forces any liquid refrigerant out of receiver tank through the drier, heat exchanger, and expansion valve to the
evaporator.
From which it returns to the compressor through the heat exchanger, accumulator, (and ETV T-Series).
Solenoid and Check Valves
1. Condenser Inlet Solenoid (CIS)-Closed/ Energized
2. Condenser Check Valve-Closed
3. Receiver Tank Pressure Check Valve-Open
4. Hot Gas Solenoid (HGS)-Open/Energized
5
4
3
Cool Mode T-500R/T-Dairy
Unit Description
6
2
1
5-18