Thermo King T-1000R Maintenance Manual Download Page 45

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Unit Description

5-11

REFRIGERATION SYSTEM COMPONENTS

The the refrigeration system is these units does not have a three-way valve. Instead, it uses a condenser inlet solenoid (CIS)

and a hot gas solenoid. Some of the main components are briefly described below.

Solenoids and Valves

Condenser Inlet Solenoid (CIS)

This valve stops the flow of refrigerant to the condenser. This solenoid is energized (closed) when the unit is operating in the

heat and defrost modes. This is a normally open valve.

Condenser Check Valve

This check valve prevents refrigerant from migrating from the receiver tank back into the condenser during the heat and defrost

modes.

Hot Gas Solenoid (HGS)

This valve is energized (open) in the heat and defrost modes. It allows hot gas to enter the evaporator coil. This is a normally

closed valve.

Electronic Throttling Valve (ETV) (T-1200R/T-1200R Spectrum)

This is an electronic valve that the microprocessor uses to control the suction pressure to the compressor. The ETV is a variable

position valve operated by a stepper motor. The ETV system also uses discharge and suction pressure transducers. The ETV is
not used if the unit is equipped with an SPR.

Suction Pressure Regulator (SPR) (T-500R/T-Dairy/T-Series Except T-1200R)

This component is a mechanical control device used to limit the suction pressure to the compressor. The valve controls suction

pressure based on the actual system pressure.

Receiver Tank Pressure Check Valve

This check valve allows hot gas to force the liquid refrigerant out of the receiver tank during the heat and defrost modes. It

prevents refrigerant from migrating from the receiver tank to the hot gas line during the cool mode.

Purge Valve (PV)

The purge valve is energized (open) in the purge mode (and in heat and defrost modes) to move the refrigerant out of the

condenser to ensure adequate refrigerant is available. This is a normally closed valve.

Purge Check Valve (T-500R/T-Dairy/T-Series Spectrum)

This check valve prevents refrigerant from migrating from the accumulator back into the condenser during the heat and defrost

modes.

Liquid Injection Solenoid (LIS)(UT-Series)

This valve helps control the temperature of the scroll compressor. It is energized or pulsed (open) when the scroll compressor

temperature exceeds a set value to inject liquid refrigerant directly into the compressor. The liquid refrigerant flashes to a gas to
effectively cool the compressor. This valve is normally closed.

Discharge Pressure Regulator (DPR)

This component is a mechanical control device used to maintain a minimum discharge pressure during heat and defrost. The

valve controls discharge pressure based on the actual system pressure.

Throttling Valve (UT-Series)

This component is a mechanical control device used to limit the suction pressure to the compressor.

Hot Gas Bypass Solenoid (HGBS) (UT SPECTRUM)

This normally closed valve helps regulate compressor suction pressure. If the suction pressure falls below a set limit, this valve

is energized (open) to allow high pressure refrigerant gas from the discharge line to flow into the suction line to raise suction
pressure to an acceptable level.

Receiver Tank Pressure Solenoid (RTPS) (T-800R SPECTRUM/T-1000R SPECTRUM/T-1200R SPECTRUM/UT
SPECTRUM)

This normally closed valve is energized (open) when any zone is operating in heat or defrost mode and the refrigerant

discharge pressure is low. It pressurizes the receiver tank to push stored liquid refrigerant into the system. This insures adequate
refrigerant is available to heat or defrost the zone.