Unit Not Cooling / High Temperature

Low Coolant Level

Engine coolant level is below recommended operating limits.

Alarm 10 – Supply Air Temperature Sensor (SATS) Out of Range

Carrier Transicold alarm AL10 (Alarm Code 10) means the Advance microprocessor has detected the Supply Air Temperature Sensor (SATS/STS) reading is out of range, open, or shorted. The SATS lives in the discharge airstream after the evaporator on Vector, X4, X2 and Supra reefer units and is the primary control sensor when 'Supply' is selected. When AL10 latches, the controller falls back to the Return Air Sensor and box temperature control becomes unstable — a frequent cause of load-quality claims.

High Coolant Temp

Engine temperature has exceeded the maximum safe operating limit.

High Discharge Pressure

Refrigerant discharge pressure exceeded the safety limit.

Alarm 17 – High Compressor Discharge Temperature (CDT)

Carrier Transicold alarm code 17 (AL17) triggers when Compressor Discharge Temperature (CDT) climbs above the safety threshold — typically 310°F (154°C) on Vector, X4, X2 and Supra reefer units. The Advance controller shuts the unit down to protect the compressor from thermal breakdown of oil, valve plate damage, and burned windings. AL17 almost always points at a refrigerant-side or airflow problem, not the compressor itself.

Compression Ratio Exceeded

Pressure ratio between suction and discharge out of range.

Check Refrig System

The system detected poor cooling efficiency.

Check Coolant Temp

Engine temperature is not rising or is out of expected range.

Box Temp Out of Range

The temperature inside the box is outside the established tolerance range relative to the setpoint.

C2 Box Temp Out of Range

Second compartment (C2) temperature is outside allowable limits.

C3 Box Temp Out of Range

Third compartment (C3) temperature is outside allowable limits.

Compressor Motor Overload

The compressor motor overload relay has tripped due to excessive current.

Condenser Motor Overheated

The condenser fan motor thermal sensor reports excessive temperature.

Evap Motor Overheated

The evaporator fan motor is operating above its safe temperature threshold.

Check Remote Cool Light

A problem has been detected in the remote cooling indicator light (Cool Light) circuit.

Check High Temperature Thermostat

Activation of the high temperature thermostat (Overheat protection).

Check Ambient Air Sensor

Ambient air temperature sensor failure.

Check Return Air Sensor

Failure in the return air temperature sensor.

Check Supply Air Sensor

Fault detected on the supply air temperature sensor (SAS). If the unit shut down, repair immediately; otherwise report and repair at end of trip.

Check Comp Discharge Sensor

An abnormal reading is detected at the compressor discharge temperature sensor.

Check Suction Temp Sensor

Failure in the suction temperature sensor circuit.

Check Engine Coolant Sensor

Failure in the engine coolant temperature sensor.

Check Evap Temp Sensor

Failure detected in the evaporator coil temperature sensor.

Check Remote Temp Sensor 1

Signal error in remote temperature sensor number 1.

Check Remote Temp Sensor 2

Signal error in remote temperature sensor number 2.

Check Remote Temp Sensor 3

Signal error in remote temperature sensor number 3.

Pretrip Stopped By User

The Pretrip test was manually canceled by the operator.

Check Coolant Temp Sensor

Engine coolant temperature sensor failure detected during Pretrip.

Check Ambient Air Sensor

Ambient air temperature sensor reports erratic values or is disconnected.

Check Disch Temp Sensor

Compressor discharge temperature sensor out of range.

Check Suction Temp Sensor

Compressor suction temperature sensor is not responding correctly.

Check Economizer

Economizer performance is insufficient or null.

Check Evap Superheat

Evaporator superheat is outside design limits.

Check Evap Outlet Temp

The evaporator outlet temperature sensor does not respond correctly during tests.

High Discharge Pressure

Dangerously high discharge pressure; risk of high pressure cutout.

Setpoint Error

Error detected in the setpoint configuration or reading.

Low Discharge Superheat

Low discharge superheat detected; risk of liquid floodback to the compressor.

High Economizer Superheat

High superheat at the economizer; reduced cooling efficiency.

No Setpoint Change

An attempt to change the setpoint was made but could not be validated in the main zone.

No Setpoint Change C2

Error when attempting to change the setpoint in compartment 2 (C2).

No Setpoint Change C3

Error when attempting to change the setpoint in compartment 3 (C3).

C2 Check High Temp Thermostat

Compartment 2 high temperature thermostat activated or failed.

C3 Check High Temp Thermostat

Compartment 3 high temperature thermostat activated or failed.

Economizer Temp Sensor

Malfunction in the economizer temperature sensor.

C2 Chk Evap Temp Sensor

Indicates a problem with the evaporator temperature sensor in compartment 2.

C2 Chk Evap Outlet Temp

Error in compartment 2 evaporator outlet temperature detected during Pre-Trip.

C3 Chk Evap Outlet Temp

Error in compartment 3 evaporator outlet temperature detected during Pre-Trip.

C2 Chk Evap1 Superheat

Superheat out of range in evaporator 1 of compartment 2.

Engine Over Heat ENCU

Engine has exceeded the maximum safety temperature limit configured by the ENCU.

Water Temp Low ENCU

Coolant temperature too low; engine failing to reach operating temperature.

Water Temp High ENCU

High coolant temperature detected by the Engine Control Unit (warning threshold).

EES Filter Inlet Temp

Error in the temperature sensor signal at the DPF filter inlet.

EES Filter Outlet Temp

Error in the temperature reading recorded at the exhaust system filter outlet.

EES Exhaust Inlet Temp

Abnormal temperature or reading error at the exhaust gas inlet.

EES ECU Temp Low

Internal temperature of the control unit is below the safe operating limit.

EES ECU Temp High

Internal temperature of the control unit has exceeded the maximum allowed.

EES No Temperature Rise

The system attempted an active regeneration but did not detect the expected temperature increase.

EES System Overtemp

Temperature in the aftertreatment system has exceeded structural safety limits.

Temp Sensor Drift

Unacceptable difference between readings of various temperature sensors.

Check (Control) Return Air Sensor (Zone)

Failure of the return air sensor, responsible for measuring the cargo temperature.

Check Ambient Temp Sensor

The exterior ambient temperature sensor presents a reading failure.

Check Coolant Temp Sensor

Failure in the sensor that monitors the diesel engine coolant temperature.

Unit Running on Coil Sensor (Zone)

The system is using the coil sensor to control temperature due to a main sensor failure.

High Evaporator Temperature (Zone)

An excessively high evaporator temperature has been detected.

High Discharge Pressure (or Temperature)

The compressor discharge pressure or temperature has exceeded safety limits.

Unit or Zone Controlling on Alternate Sensor (Zone)

The unit is controlling temperature based on a secondary or alternate sensor.

Sensor or Digital Input Shutdown (Zone)

A critical digital input or sensor has triggered a complete unit shutdown.

Sensor Check (Zone)

The microprocessor has detected an unusual discrepancy between temperature sensors.

Defrost Terminated by Time

The defrost cycle ended due to maximum time limit instead of temperature termination.

High Engine Coolant Temperature

The diesel engine has reached a temperature above the safety limit.

Cooling Cycle Check (Zone)

The system detects insufficient cooling capacity during monitoring.

Cooling Cycle Fault (Zone)

Critical system failure preventing cooling; unit shuts down to protect cargo.

Heating Cycle Fault (Zone)

Critical failure preventing the unit from generating heat when required.

Check Refrigeration Capacity (Zone)

Refrigeration capacity is lower than expected for the current setpoint.

Refrigeration Capacity Low (Zone)

The unit or zone is not reaching the expected cooling capacity and has been stopped for safety.

Check Engine Coolant Level

The level sensor detects that the engine coolant is below the safe limit.

Check Engine Coolant Temp

Engine coolant temperature is unusually high or the sensor is failing.

Unit Forced to Low Speed

The unit has restricted operation to low speed to protect the engine or system.

Remote Sensor Shutdown

Critical failure in a remote temperature sensor that prevents safe operation.

Abnormal Temperature Differential (Zone)

Abnormal temperature differential detected in a specific zone (evaporator).

Check Compressor Temp Sensor

Compressor temperature sensor circuit is out of range or faulty.

High Compressor Temp

The compressor temperature is unusually high, approaching the safety limit.

High Compressor Temp Shutdown

The unit stopped to protect the compressor due to excessive temperature.

Low Engine Coolant Temp

Engine coolant temperature is too low for normal operation.

Restart Null

The unit was unable to restart automatically after a nullified stop.

ETV Fault – Electronic Throttling Valve Circuit (Code 89)

Thermo King alarm code 89 indicates a failure in the Electronic Throttling Valve (ETV) control circuit. The ETV is a stepper-motor modulating valve in the suction line that regulates suction pressure and compressor loading on Thermo King SB-, SLXi, SLXe, SLX, SLX Whisper, T-Series, Precedent and TriPac reefer units. When the microprocessor cannot drive or read the ETV stepper coils correctly, it logs Code 89 and forces the unit into a protective mode — often unable to hold setpoint or pull down.

Failed Remote Return Air Sensor (CR)

Remote return air sensor failure preventing accurate zone temperature reading.

High Compressor Pressure Ratio

Excessive pressure ratio detected between compressor suction and discharge, risking mechanical integrity.

Controlling on Evap Coil Outlet Temp (CR)

Unit is controlling temperature based on evaporator outlet due to a primary sensor failure.

Low Evaporator Coil Temperature (CR)

Evaporator coil temperature is dangerously low, which may lead to icing or freezing.

Check High Discharge Pressure Sensor

Error in the high discharge pressure sensor (Replaced by code 86 in newer models).

Unit Not Configured Correctly (Zone)

The unit configuration does not match the hardware or number of zones installed.

Check High Pressure Cut Out Switch

Fault in the High Pressure Cut Out (HPCO) switch or its circuit.

Check PMW Liquid Injection Circuit

Failure in the Pulse Width Modulation (PMW) liquid injection circuit, crucial for compressor cooling.

Check Evap Coil Inlet Temp Sensor (CR)

Failure in the evaporator coil inlet temperature sensor (CR).

Check Evap Coil Outlet Temp Sensor (CR)

Failure in the evaporator coil outlet temperature sensor (CR).

Check Back Pressure Regulator (CR)

Indicates a problem with the suction pressure regulator or back pressure regulator, affecting temperature stability.

Setpoint Not Entered (Zone)

An active zone in the multi-temperature system has been detected without a defined setpoint.

Check Multi-Temp Fan Speed Control Output (Zone)

Error in the speed control of the multi-temperature evaporator fans.

Sensor Out of Range High (DAS and HMI) (Zone)

A sensor is reporting a measurement above the maximum allowed limit.

Check CO2 Tank Pressure Sensor (CR)

Failure in the sensor monitoring CO2 tank pressure in cryogenic systems.

Check Display Return Air Sensor (Zone)

The display return air temperature sensor is presenting erroneous readings.

Check Display Discharge Air Sensor (Zone)

The display discharge air temperature sensor is presenting erroneous readings.

High Engine Coolant Temperature Check

The engine coolant has exceeded the safety temperature threshold.

Check Auxiliary Coolant Temp Sensor

Fault in the auxiliary coolant temperature sensor circuit.

Engine Wait to Start Time Delay Expired

The preset wait time for start-up preheating (glow plugs) has expired.

Low Compressor Discharge Pressure (Scroll Only)

Scroll compressor discharge pressure too low during operation.

Minimum ETV Discharge Superheat Temp (Scroll)

ETV controlled discharge superheat is at the minimum thermal limit.

Battery Charger External/Environmental Fault

Battery charger failure caused by external or environmental factors.

Battery Temperature Sensor Alarm

Battery temperature sensor reports out of range readings or is disconnected.

Battery Charger Fault – Unit Forced to Low Speed

The battery charger has a fault, and the unit is forced to low speed to protect the system.

Battery Charger Operating Bulk Voltage Out of Range

The charging voltage during the 'Bulk' stage is outside the normal operating range.

Battery Charger Temperature Below Operating Range

The battery charger temperature is below the minimum operating range.

Battery Charger Internal Temp Sensor Fault

Fault in the sensor monitoring the internal temperature of the battery charger.

Check Coolant Temp Sensor

Engine coolant temperature sensor error.

Check Fresh Air Temp Sensor

Fault in the sensor measuring outside ambient air temperature.

Check Fuel Temperature Sensor

Fault in the fuel temperature sensor circuit.

Check EGR System

Incorrect flow or failure detected in the Exhaust Gas Recirculation (EGR) system.

Check EGR Temperature Sensor

Failure in the sensor monitoring the temperature of the EGR system gases.

Check Intake Air Temperature Sensor

Error in the Intake Air Temperature (IAT) sensor for the engine.