Error Code	Symptom	Fault Type	Guide
E0	Indoor unit will not run, display shows E0 shortly after power-up	Indoor Unit EEPROM / Main PCB Communication Fault	View Details
E1	Indoor unit stops and displays E1, outdoor unit does not respond	Indoor–Outdoor Communication Failure	View Details
E2	Indoor unit stops cooling and displays E2, fan may continue running	Indoor Evaporator Coil Freeze Protection / Anti-freeze Protection	View Details
E3	Outdoor unit stops and E3 is shown on indoor display, poor or no cooling	Outdoor Fan or Overcurrent Protection / Compressor Overload	View Details
E4	Unit stops and displays E4, often during heating mode on heat pump models	High Discharge Temperature Protection / Compressor Discharge Overheat	View Details
E5	Unit stops and displays E5, may occur shortly after startup	Overcurrent Protection / Compressor Overload Trip	View Details
E6	Indoor unit shows E6, system does not start or stops shortly after starting	Indoor Fan Motor Fault / DC Fan Motor Feedback Error	View Details
E7	Indoor unit displays E7, outdoor unit may not start	Mode Conflict / Reversed Valve or Indoor–Outdoor Mode Mismatch	View Details
E8	Unit stops and displays E8, often during high load operation	High Pressure Protection / Overload Protection	View Details
E9	Indoor unit shows E9, unit may shut down unexpectedly	Water Overflow Protection / Full Drain Pan Alarm	View Details
F0	Unit displays F0 and stops cooling, may restart after power cycle	Low Refrigerant / Refrigerant Leakage Protection	View Details
F1	Indoor unit displays F1, unit may run but with poor temperature control	Indoor Ambient Temperature Sensor (Room Sensor) Fault	View Details
F2	Indoor unit displays F2, unit may shut down or run erratically	Indoor Evaporator Temperature Sensor Fault	View Details
F3	Indoor unit shows F3, often associated with outdoor temperature sensing issues	Outdoor Ambient Temperature Sensor Fault	View Details
F4	Indoor unit displays F4, system may not heat or cool correctly	Outdoor Condenser Coil Temperature Sensor Fault	View Details
F5	Indoor unit shows F5, unit may stop during defrost or heating	Defrost Temperature Sensor / Outdoor Coil Sensor Fault	View Details
F6	Indoor unit displays F6, compressor may not start or may shut down quickly	Compressor Low Frequency Protection / Inverter Drive Fault	View Details
F7	Indoor unit shows F7, abnormal heating or cooling performance	Indoor–Outdoor Capacity Mismatch / Frequency Restriction	View Details
F8	Indoor unit displays F8, unit may run at reduced capacity	Indoor Fan Speed Out of Control / Feedback Error	View Details
F9	Indoor unit shows F9, irregular temperature control or shutdowns	Indoor Coil Outlet Temperature Sensor Fault	View Details
H0	Display shows H0, unit may not respond to remote commands	Indoor PCB EEPROM Parameter Error	View Details
H1	Display shows H1, unit does not heat, outdoor unit may be in defrost	Defrost Mode Active (Information Code)	View Details
H2	Display shows H2, heating performance is poor or unit stops	Compressor Overheat Protection in Heating	View Details
H3	Indoor unit shows H3, system shuts down to protect compressor	Compressor Overload Protection / Overheat	View Details
H4	Indoor unit displays H4, unit may not start or may stop mid-cycle	Indoor–Outdoor Mismatch / EEPROM Compatibility Error	View Details
H5	Indoor unit shows H5, outdoor unit may not run	IPM (Intelligent Power Module) Protection / Inverter Module Fault	View Details
H6	Indoor unit displays H6, outdoor fan may not operate correctly	Outdoor Fan Motor Fault	View Details
H7	Indoor unit shows H7, compressor does not start	Compressor Position Protection / Inverter Startup Fault	View Details
H8	Indoor unit displays H8, water leakage protection active on some models	Indoor Drain Pump or Water Level Protection	View Details
H9	Indoor unit shows H9, poor heating performance	Indoor Coil Low Temperature Protection in Heating	View Details
–	Air conditioner runs but does not cool the room effectively	Insufficient Cooling Capacity / Performance Degradation	View Details
–	Breaker trips when air conditioner starts or shortly after	Overcurrent / Electrical Short	View Details
–	Display shows normal but airflow from indoor unit is very weak	Reduced Indoor Airflow	View Details
–	Frost or ice forming on indoor evaporator coil	Evaporator Icing	View Details
–	Frost or ice forming on outdoor unit piping or coil	Outdoor Coil Icing (Cooling Mode) or Abnormal Defrost (Heating Mode)	View Details
–	Indoor unit emits unpleasant musty or moldy odor when starting	Biological Growth on Evaporator Coil and Drain Pan	View Details
–	Indoor unit leaks water from the front panel or bottom	Condensate Drainage Failure	View Details
–	Indoor unit makes clicking or popping noises during operation	Thermal Expansion and Plastic Casing Noise	View Details
–	Loud buzzing or grinding noise from outdoor unit	Outdoor Mechanical Noise / Fan or Compressor Issue	View Details
–	Loud rattling or buzzing noise from indoor unit during operation	Indoor Mechanical Vibration / Loose Components	View Details
–	Outdoor unit is running but indoor fan does not blow air	Indoor Blower Failure	View Details
–	Remote control does not operate the indoor unit	IR Communication Failure	View Details
–	Unit blows cold air in heating mode (heat pump models)	Reversing Valve Stuck or Control Fault	View Details
–	Unit blows warm air in cooling mode	Loss of Cooling / Reversing Valve or Refrigerant Issue	View Details
–	Unit frequently turns on and off (short cycling)	Short Cycling / Improper Control or Sizing	View Details
–	Unit powers on but compressor never starts, only fan runs	Compressor Non-Start Condition	View Details
–	Unit will not power on at all, no lights or display	No Power / Power Supply Failure	View Details

Tosot Air Conditioners Error Codes

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