Thermo King SLXi Spectrum, Maintenance Manual

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Unit Description 5-3
The µP-IV, µP-V or µP-VI controller is a programmable microprocessor that controls all unit functions to maintain the cargo at
the proper temperature. The controller integrates the following functions: thermostat, digital thermometer, defrost timer,
CYCLE-SENTRY system, hourmeters, oil pressure gauge, coolant temperature gauge, ammeter, voltmeter, tachometer, mode
indicator, refrigeration system controller and diagnostic system. µP-VI controller replaces the oil pressure reading with oil
pressure status; and also integrates the discharge and suction pressure gauges and ETV position counter on (SL-400 models only).
Smart Reefer 2 Microprocessor (SR-2)
The Smart Reefer 2 (SR-2) is used on some SL-400, all SL-400e and SLX models. The SR-2 controller is a programmable
microprocessor that controls all unit functions to maintain the cargo at the proper temperature. The SR-2 integrates the following
functions: changing setpoint and operating mode, viewing gauge/sensor and hourmeter readings, initiating Defrost cycles,
viewing and clearing alarms.
Smart Reefer 3 Microprocessor (SR-3)
The Smart Reefer 3(SR-3) is used on some SLX and all SLXe and SLXi models. The SR-3 controller is a programmable
microprocessor that controls all unit functions to maintain the cargo at the proper temperature. The SR-3 integrates the following
functions: changing setpoint and operating mode, viewing gauge/sensor and hourmeter readings, initiating Defrost cycles,
viewing and clearing alarms.
Service Test Mode (Standard on TG-VI, µP-IV, µP-V, µP-VI, SR-2 and SR-3 Controllers)
Technicians can use the Service Test mode to place a unit in a specific operating mode for 15 minutes, regardless of setpoint or
temperature sensor inputs. This allows technicians to operate the unit under known conditions while performing diagnosis and
service procedures.
Electric Standby Motors
SL, SLe, SLXe and SLXi model 50 units feature a 9.3 kW, 60/50 Hz electric drive motor.
SLX and SLX Ferry units feature a 14.7 kW, 60/50 Hz electric drive motor.
Refrigeration Modulation Option
SL, SLe, SLX, SLXe and SLXi models are available with an optional refrigeration modulation system. The modulation system
provides very precise control of the compartment temperature.
As the temperature of the return air approaches the controller setpoint, the modulation system gradually closes the modulation
valve in the suction line between the evaporator and heat exchanger. The modulation valve closes more as the return air
temperature gets closer to the setpoint. When the temperature is near setpoint, the modulation valve is virtually closed and the
hot gas bypass valve opens. This allows hot gas to enter the evaporator coil, further minimising the temperature difference across
the evaporator coil.
When the cargo temperature begins to increase above setpoint, the modulation valve begins to open. The hot gas bypass valve
remains open until the modulation valve is completely open. The hot gas bypass valve then closes. This operation provides very
smooth and steady temperature control.
In order to improve fuel economy for SLXi unit models, the modulation function remains the same with the exception that
Hot Gas Bypass pulses instead of remaining open.
Discharge Air Modulation Control
The µP-VI, SR-2 and SR-3 Controllers have a selection that allows modulation to be controlled by either the return air
temperature or the discharge air temperature.
Electronic Throttling Valve
The following models feature an electronic throttling valve (ETV) as standard:
• SL-400, SL-400e, SLX/SLXe/SLXi 300/400
• SLX Spectrum manufactured as from 05/2012
• SLXe/SLXi Spectrum
The electronic throttling valve (ETV) is a variable position valve operated by a stepper motor. The ETV system also includes
a suction pressure transducer, discharge pressure transducer and a hot gas bypass valve.