Viessmann Air Conditioners Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
Advertisements
A0
Indoor unit does not start; display shows A0 shortly after power-on.
Indoor-Outdoor Communication Fault
A1
Indoor unit runs briefly then stops; A1 displayed on indoor unit.
Indoor Room Temperature Sensor (NTC) Fault
A2
Indoor unit stops cooling; A2 error on display.
Indoor Coil (Evaporator) Temperature Sensor Fault
A3
Indoor unit stops and A3 error appears; sometimes accompanied by water dripping from the front panel.
Condensate Drain Pump Fault / Float Switch Activation
A4
Indoor unit stops and A4 error appears; unit may short-cycle in heating mode (for heat pump models).
Indoor Heat Exchanger Overheat / Protection
A5
Indoor unit stops in heating mode; A5 error shown; outdoor unit may still run briefly.
Indoor Heat Exchanger Freeze / Frost Protection
A6
Indoor unit attempts to start but the fan does not run; A6 error displayed.
Indoor Fan Motor Fault
C0
System does not respond to remote; C0 appears on the display or service menu.
Remote Control / Signal Reception Fault
C4
Unit runs, but performance is unstable; C4 appears in diagnostics.
Outdoor Coil Temperature Sensor Fault
C5
Outdoor unit stops unexpectedly; C5 error logged; may occur during defrost cycles.
Outdoor Discharge Pipe Temperature Sensor Fault
C9
Outdoor unit fails to start or stops; C9 error in diagnostics.
Outdoor Ambient Temperature Sensor Fault
E0
System does not start; E0 displayed on the indoor unit.
EEPROM / Configuration Data Error
E1
Indoor unit stops; E1 error displayed; may occur shortly after compressor start.
High-Pressure Protection / Refrigerant Circuit Overpressure
E2
Unit stops cooling; E2 error; may be accompanied by frost on the indoor coil.
Low-Pressure Protection / Evaporator Freeze
E3
Outdoor unit does not start; E3 error displayed; compressor remains off.
Outdoor Unit Overcurrent / Compressor Overload
E4
System stops; E4 error; may occur during heating mode on heat pump models.
Discharge Temperature High Protection
E5
Outdoor unit shuts down; E5 error; may be intermittent.
Inverter Module Overcurrent / IPM Protection
E6
Indoor unit shows E6; outdoor unit may not respond; no cooling or heating.
Indoor–Outdoor Communication Error
E7
Indoor unit displays E7; louver may not move correctly.
Indoor Louver/Stepper Motor Fault
E8
Indoor unit stops; E8 error; may be associated with very low indoor airflow.
Indoor Fan Speed Feedback Error
F0
System stops; F0 error; may occur during cooling startup.
Refrigerant Undercharge/Low Refrigerant Protection
F1
Indoor unit shows F1; unit may run with poor temperature control.
Indoor Room Temperature Sensor Out of Range
F2
Indoor unit shows F2; coil temperature reading appears abnormal in diagnostics.
Indoor Coil Sensor Out of Range
F3
Outdoor unit shows F3; poor heating performance on heat pump models.
Outdoor Coil Sensor Out of Range
H0
System locked out; H0 or similar lock code displayed; settings cannot be changed.
Child Lock/Keypad Lock Activated
H1
Heating mode delayed; H1 displayed; outdoor unit not starting immediately.
Defrost/Anti-Cold Air Protection (Informational)
P0
System stops; P0 error; may occur under heavy load.
DC Bus Voltage Protection
P1
System stops; P1 error; may be intermittent with power fluctuations.
Low Voltage Protection
P2
System stops; P2 error; often occurs during high ambient temperatures.
High Temperature Protection of Compressor or Inverter
P4
System stops; P4 error; may be associated with abnormal compressor behavior.
Inverter Module Temperature Sensor Fault
Symptom
Burning or electrical smell from indoor or outdoor unit.
Overheating Electrical Component
Symptom
Indoor unit blows warm air in cooling mode even though compressor is running.
Refrigerant Flow Misrouting / 4-Way Valve Stuck (Heat Pump)
Symptom
Indoor unit displays temperature, but does not respond to remote commands.
Remote Signal Reception Failure
Symptom
Indoor unit fan runs, but outdoor unit does not start; no error code shown.
Outdoor Unit Not Responding
Symptom
Indoor unit leaking water from front panel or dripping onto wall.
Condensate Drain Blockage
Symptom
Indoor unit louver does not move or is stuck in one position.
Louver Mechanism Jam
Symptom
Indoor unit makes loud rattling or buzzing noise during operation.
Indoor Mechanical Vibration / Loose Components
Symptom
Indoor unit runs but no cooling; air temperature hardly changes.
Loss of Cooling Capacity
Symptom
Outdoor unit runs, but indoor fan does not start; coil gets cold and may ice up.
Indoor Fan Not Running
Symptom
Outdoor unit very noisy (grinding or scraping) when running.
Outdoor Fan or Compressor Mechanical Noise
Symptom
Unit frequently trips the circuit breaker when starting.
Excessive Inrush Current / Electrical Overload
Symptom
Unit starts then stops after a few minutes; short cycling without error code.
Short Cycling / Incorrect Capacity Control
Symptom
Unit will not start at all; no lights on indoor display.
No Power / Power Supply Failure
Symptom
Unpleasant musty or moldy smell when the air conditioner starts.
Biological Growth on Evaporator and Drain Pan
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| A0 |
Indoor unit does not start; display shows A0 shortly after power-on.
|
Indoor-Outdoor Communication Fault | View Details |
| A1 |
Indoor unit runs briefly then stops; A1 displayed on indoor unit.
|
Indoor Room Temperature Sensor (NTC) Fault | View Details |
| A2 |
Indoor unit stops cooling; A2 error on display.
|
Indoor Coil (Evaporator) Temperature Sensor Fault | View Details |
| A3 |
Indoor unit stops and A3 error appears; sometimes accompanied by water dripping from the front panel.
|
Condensate Drain Pump Fault / Float Switch Activation | View Details |
| A4 |
Indoor unit stops and A4 error appears; unit may short-cycle in heating mode (for heat pump models).
|
Indoor Heat Exchanger Overheat / Protection | View Details |
| A5 |
Indoor unit stops in heating mode; A5 error shown; outdoor unit may still run briefly.
|
Indoor Heat Exchanger Freeze / Frost Protection | View Details |
| A6 |
Indoor unit attempts to start but the fan does not run; A6 error displayed.
|
Indoor Fan Motor Fault | View Details |
| C0 |
System does not respond to remote; C0 appears on the display or service menu.
|
Remote Control / Signal Reception Fault | View Details |
| C4 |
Unit runs, but performance is unstable; C4 appears in diagnostics.
|
Outdoor Coil Temperature Sensor Fault | View Details |
| C5 |
Outdoor unit stops unexpectedly; C5 error logged; may occur during defrost cycles.
|
Outdoor Discharge Pipe Temperature Sensor Fault | View Details |
| C9 |
Outdoor unit fails to start or stops; C9 error in diagnostics.
|
Outdoor Ambient Temperature Sensor Fault | View Details |
| E0 |
System does not start; E0 displayed on the indoor unit.
|
EEPROM / Configuration Data Error | View Details |
| E1 |
Indoor unit stops; E1 error displayed; may occur shortly after compressor start.
|
High-Pressure Protection / Refrigerant Circuit Overpressure | View Details |
| E2 |
Unit stops cooling; E2 error; may be accompanied by frost on the indoor coil.
|
Low-Pressure Protection / Evaporator Freeze | View Details |
| E3 |
Outdoor unit does not start; E3 error displayed; compressor remains off.
|
Outdoor Unit Overcurrent / Compressor Overload | View Details |
| E4 |
System stops; E4 error; may occur during heating mode on heat pump models.
|
Discharge Temperature High Protection | View Details |
| E5 |
Outdoor unit shuts down; E5 error; may be intermittent.
|
Inverter Module Overcurrent / IPM Protection | View Details |
| E6 |
Indoor unit shows E6; outdoor unit may not respond; no cooling or heating.
|
Indoor–Outdoor Communication Error | View Details |
| E7 |
Indoor unit displays E7; louver may not move correctly.
|
Indoor Louver/Stepper Motor Fault | View Details |
| E8 |
Indoor unit stops; E8 error; may be associated with very low indoor airflow.
|
Indoor Fan Speed Feedback Error | View Details |
| F0 |
System stops; F0 error; may occur during cooling startup.
|
Refrigerant Undercharge/Low Refrigerant Protection | View Details |
| F1 |
Indoor unit shows F1; unit may run with poor temperature control.
|
Indoor Room Temperature Sensor Out of Range | View Details |
| F2 |
Indoor unit shows F2; coil temperature reading appears abnormal in diagnostics.
|
Indoor Coil Sensor Out of Range | View Details |
| F3 |
Outdoor unit shows F3; poor heating performance on heat pump models.
|
Outdoor Coil Sensor Out of Range | View Details |
| H0 |
System locked out; H0 or similar lock code displayed; settings cannot be changed.
|
Child Lock/Keypad Lock Activated | View Details |
| H1 |
Heating mode delayed; H1 displayed; outdoor unit not starting immediately.
|
Defrost/Anti-Cold Air Protection (Informational) | View Details |
| P0 |
System stops; P0 error; may occur under heavy load.
|
DC Bus Voltage Protection | View Details |
| P1 |
System stops; P1 error; may be intermittent with power fluctuations.
|
Low Voltage Protection | View Details |
| P2 |
System stops; P2 error; often occurs during high ambient temperatures.
|
High Temperature Protection of Compressor or Inverter | View Details |
| P4 |
System stops; P4 error; may be associated with abnormal compressor behavior.
|
Inverter Module Temperature Sensor Fault | View Details |
| – |
Burning or electrical smell from indoor or outdoor unit.
|
Overheating Electrical Component | View Details |
| – |
Indoor unit blows warm air in cooling mode even though compressor is running.
|
Refrigerant Flow Misrouting / 4-Way Valve Stuck (Heat Pump) | View Details |
| – |
Indoor unit displays temperature, but does not respond to remote commands.
|
Remote Signal Reception Failure | View Details |
| – |
Indoor unit fan runs, but outdoor unit does not start; no error code shown.
|
Outdoor Unit Not Responding | View Details |
| – |
Indoor unit leaking water from front panel or dripping onto wall.
|
Condensate Drain Blockage | View Details |
| – |
Indoor unit louver does not move or is stuck in one position.
|
Louver Mechanism Jam | View Details |
| – |
Indoor unit makes loud rattling or buzzing noise during operation.
|
Indoor Mechanical Vibration / Loose Components | View Details |
| – |
Indoor unit runs but no cooling; air temperature hardly changes.
|
Loss of Cooling Capacity | View Details |
| – |
Outdoor unit runs, but indoor fan does not start; coil gets cold and may ice up.
|
Indoor Fan Not Running | View Details |
| – |
Outdoor unit very noisy (grinding or scraping) when running.
|
Outdoor Fan or Compressor Mechanical Noise | View Details |
| – |
Unit frequently trips the circuit breaker when starting.
|
Excessive Inrush Current / Electrical Overload | View Details |
| – |
Unit starts then stops after a few minutes; short cycling without error code.
|
Short Cycling / Incorrect Capacity Control | View Details |
| – |
Unit will not start at all; no lights on indoor display.
|
No Power / Power Supply Failure | View Details |
| – |
Unpleasant musty or moldy smell when the air conditioner starts.
|
Biological Growth on Evaporator and Drain Pan | View Details |
No matching codes found
Advertisements