Error Codes

The main control panel detects that the system's working current has exceeded the upper protection limit. The unit stops running and displays E0.

1. For fixed-frequency models: confirm the live wire passes through the current transformer correctly. If not, reroute the wire and reboot.
2. Use a current clamp to measure working current and compare against the nameplate range. If current is within range, the current transformer itself may be faulty — replace the indoor unit main control panel.
3. Measure supply voltage and confirm it falls within the normal operating range. If abnormal, investigate local grid stability.
4. If working current exceeds the nameplate range and supply voltage is normal, the system may be blocked or the unit overloaded. Inspect based on actual site conditions.

The main control panel in the indoor unit detected a short circuit or open circuit condition on the internal temperature sensor.

1. Measure sensor resistance. For inverter models it should be approximately 15KΩ at 25°C. Check for short circuit or open circuit.
2. Inspect the sensor wire for breaks or damage.
3. Verify all terminal connectors are firmly seated. Check for loose solder joints between the terminal and the main control panel. Gently tug the terminal if needed.
4. Check whether the sensor has moisture damage.
5. If no standard sensor is available, swap in a nearby sensor temporarily. If the error clears, replace the original sensor. If the error persists, inspect and potentially replace the main internal control panel.

The main external control panel detected a short circuit or open circuit condition on the external coil sensor.

1. Measure sensor resistance. For inverter models it should be approximately 20KΩ at 25°C. Check for short circuit or open circuit.
2. Inspect the sensor wire for breaks or damage.
3. Verify all terminal connectors are firmly seated. Check for loose solder joints between the terminal and the main control panel.
4. Check whether the sensor has moisture damage. Coil sensors are especially susceptible to moisture when the sensor lead runs above the copper pipe.
5. If no standard sensor is available, swap in a nearby sensor temporarily. If the error clears, replace the original sensor. If the error persists, inspect and potentially replace the main external control panel.

The main internal control panel detected a short circuit or open circuit condition on the internal coil sensor.

1. Measure sensor resistance. For inverter models it should be approximately 20KΩ at 25°C. Check for short circuit or open circuit.
2. Inspect the sensor wire for breaks or damage.
3. Verify all terminal connectors are firmly seated. Check for loose solder joints between the terminal and the main control panel.
4. Check whether the sensor has moisture damage. Coil sensors are especially susceptible to moisture when the sensor lead runs above the copper pipe.
5. If no standard sensor is available, swap in a nearby sensor temporarily. If the error clears, replace the original sensor. If the error persists, inspect and potentially replace the main internal control panel.

For wall-mounted PG motor models: the main internal control panel is not receiving the speed feedback signal from the PG motor. For wall-mounted and mobile DC motor models: the main internal control panel cannot receive rotational speed feedback through the DC motor's green plug connection. For floor standing sliding door models: the upper or lower photoelectric switch cannot sense the sliding door position normally. In all cases, primary causes are mechanical jam, a damaged speed feedback component, or a fault in the main internal control panel's receiving circuit.

1. Check whether the fan can run for a period before the error appears. If so, mechanical jam can be excluded as the cause.
2. Disconnect power and manually rotate the indoor fan blade to check for any resistance. Occasional fan errors may be related to bearing issues.
3. For PG motor models: reconnect the drive wire and speed feedback wire to rule out connector loosening. For DC motor models: unplug and reseat the DC motor terminal connector.
4. Check that the speed feedback plug-in terminal on the control panel is firmly seated. Gently tug if needed.
5. For DC motor models: with the unit powering on in cooling mode, monitor voltage between the second (yellow) and fourth (black) wires of the DC motor terminal. Voltage should rise gradually and the motor should begin accelerating. If the motor does not rotate, the DC motor is damaged.
6. Swap in a known-good motor (without mounting it to the fan assembly). If the error persists, replace the main internal control panel. If the error clears, replace the motor.
7. For floor standing sliding door models: observe whether the sliding plate jams during startup or shutdown. If the door moves normally but the error persists, check the photoelectric switches. Verify the reversible synchronous motor is receiving 220V. Replace the faulty switch with a new sealed unit and confirm correct terminal color orientation — upper and lower photoelectric switches have different colored connectors and must not be swapped.

The frequency converter requires continuous communication between the indoor and outdoor units. When this communication cannot be established, both units indicate this error. Note: external unit power failures or other external errors can also trigger this code — distinguish pure communication failure from an external unit startup failure before diagnosing. Alternate display on some models: 5E.

1. Confirm that the indoor and outdoor units are correctly matched and connected. Power on and observe the outdoor unit — three indicator lights should illuminate then go off and the relay should pull in. If not, investigate the power supply path.
2. Verify the live and neutral wires of the indoor and outdoor units are connected to their matching counterparts. Check that the connecting wires are making solid contact.
3. Connect the black signal line S to terminal N of the outdoor unit. Power on — if E5 persists, the main external control panel may need replacement. If E5 clears, the signal connection was the issue.
4. If E5 still persists after step 3, replace the main internal control panel. If the error remains, replace the main external control panel.

Floor standing and mobile units require communication between the display board and the indoor unit main control panel. When this connection is interrupted, the display board reports this error. Only three components are involved: the main internal control panel, the connection line, and the display board.

1. Check that the connection line between the display board and main control panel is fully seated and undamaged. Re-seat or replace as needed.
2. Replace with a known-good main internal control panel. If E8 clears after rebooting, the original control panel is faulty. If E8 persists, the display board is faulty — replace it.
3. If replacing either component individually does not resolve the error, the display board and control panel may be incompatible with each other — replace both simultaneously.

The indoor unit stores operating parameters in an 8-pin EEPROM chip (EE). The main control panel motor can only run after reading this data. If the data cannot be read, this failure is indicated. Possible causes: incorrect EE chip data format; damaged EE chip; poor contact of EE chip or fault in the EE reading circuit; EE chip installed backwards.

1. Replace the internal main control panel directly.

The frequency-converting outdoor unit uses a 3-lead-wire externally driven DC motor (used after 2012). It has no speed feedback circuit — the main control panel drives it directly and monitors current balance across the three lead wires. When the panel detects imbalanced current on those wires, it indicates this error.

1. Confirm there is no mechanical jam in the external fan blades.
2. Verify the motor terminal is firmly connected and the wire order is correct. If the fan on a newly installed unit rotates in reverse, confirm the color order of the three lead wires or swap any two of the three motor wires to correct rotation direction.
3. This 3-core DC motor scheme is reliable, so the drive section of the main external control panel is the more likely failure point. Replace the main external control panel with a matched unit. If the fan returns to normal, the original control panel is faulty. If the error persists, replace the external DC motor.

The power module directly drives the compressor. When it detects overcurrent, overvoltage, or overheat, it stops the compressor and sends a shutdown request to the module panel. The resulting error is called module protection error. L-codes (L0–LC) are subdivided failures of F1 — see those entries for specific subcategory names and primary parts.

1. Check if the compressor wire order is correct. If wired in reverse, try swapping the U-V phase wires to see if the error clears.
2. Verify supply voltage stability. Measure system pressure — high pressure can cause compressor rotation problems.
3. Confirm the module panel is firmly mounted to the radiator for adequate cooling. Check if indoor or outdoor heat exchangers are dirty, which causes poor heat transfer and elevated system pressure.
4. If the error appears immediately on startup, a physical component failure is likely (unrelated to voltage or pressure). Inspect for strike-arc damage near the module panel. Use a multimeter to confirm equal resistance between any two compressor wires — should be ohm-level and equal across all pairs. Use a megameter to verify insulation resistance of each compressor wire to earth (should be MΩ level). Check that the reactor wire is firmly connected and the reactor is not damaged.
5. Test that the 15V and 5V (or 3.3V) power supplies on the module panel are stable. Rule out power supply issues originating from the main external control panel.
6. Using the diode function on the multimeter, test the power module: measure P against U, V, and W — one direction should show infinite resistance, the other a fixed on-state voltage (typically ~0.5V). Repeat for N against U, V, and W. A short circuit in any measurement indicates a damaged power module.
7. Replace the module panel with a known-good unit. If the unit runs normally after replacement, the original module panel is damaged.
8. After ruling out module, wiring, system, and power supply issues, listen to the compressor. If only electromagnetic sound is present without the compressor starting, or if the compressor runs irregularly then shuts down and indicates error, the compressor may be blocked or damaged.

See also: F3

The PFC board performs power factor correction and voltage boosting in inverter units. When it cannot complete power calibration due to overcurrent or overvoltage, it indicates this error. Depending on the model, PFC function may be integrated into the module panel or main control panel rather than a separate board.

1. Check if supply voltage is unstable or too low (below AC 135V).
2. The reactor is a core PFC component. Check if the reactor itself is damaged or if the reactor connecting wire has poor contact. Never remove the reactor and replace with a short circuit.
3. If the error appears immediately on startup, inspect for strike-arc damage near the module panel — a physical failure is likely.
4. Test that the 15V and 5V (or 3.3V) power supply on the PFC board is stable. Rule out control power issues originating from the main external control panel.
5. Replace the PFC board with a known-good unit. If the unit runs normally after replacement, the original PFC board is damaged.
6. Note: main external control panel power supply problems can also cause PFC board failures. Rule this out if PFC board replacement does not resolve the issue.
7. For models where PFC and compressor drive are integrated into a single module panel, replace the integrated panel.
8. For single-panel single-chip controllers: if PFC protection error appears with no voltage, reactor, or reactor wiring issues, replace the external unit controller directly.

The module panel monitors current on the compressor lead wires and calculates rotor position during operation. When the compressor deviates far from normal status — due to excessive current or inability to detect rotor position — this error is indicated. It frequently follows F1 (Module Protection Error) and shares a similar diagnostic approach.

1. Check if the compressor wire order is correct. If reversed, try swapping the U-V phase wires.
2. Verify supply voltage stability. Measure system pressure — high pressure causes compressor rotation problems.
3. Confirm the module panel is firmly mounted to the radiator. Check if heat exchangers are dirty, causing elevated system pressure.
4. If the error appears immediately on startup, inspect for strike-arc damage. Verify equal resistance between any two compressor wires (ohm-level, equal across all pairs). Verify insulation resistance of each compressor wire to earth (MΩ level). Also check whether DC voltage between P and N is too high (above 200V). Confirm the reactor wire is sound.
5. Test that the 15V and 5V (or 3.3V) power supplies on the module panel are stable.
6. Replace the module panel with a known-good unit. If the unit runs normally after replacement, the original module panel is damaged.
7. After ruling out module, wiring, system, and power supply issues, listen to the compressor. If only electromagnetic sound is present without startup, or if the compressor runs irregularly before shutdown, the compressor may be blocked or damaged.

See also: F1

The main external control panel detected a short circuit or open circuit condition on the exhaust sensor.

1. Measure sensor resistance. With the compressor off, resistance should be approximately 50KΩ at 25°C. After the compressor runs for a period, resistance should be between 3KΩ and 30KΩ (corresponding to 100°C–38°C exhaust temperature). Check for short circuit or open circuit.
2. Inspect the sensor wire and connecting wire for damage.
3. Verify all terminal connectors are firmly seated. Check for loose solder joints between the terminal and the main control panel.
4. Check whether the sensor has moisture damage, especially if the sensor lead runs above the copper pipe.
5. If no standard sensor is available, swap with an adjacent sensor and observe whether the error changes to a different sensor error. If so, the exhaust sensor is faulty — replace it. If the original error persists, replace the main external control panel.

The compressor top head sensor is typically a temperature protection switch that remains closed (short circuit) under normal temperature and opens (open circuit) when temperature is too high. The main external control panel indicates this error when it detects disconnection of this switch.

1. First check if the compressor top head temperature is genuinely too high (above 110°C), which would trigger the protection switch. Common causes: refrigerant shortage causing the compressor to idle, or system blockage creating excessive pressure.
2. After ruling out system issues, test the sensor terminals with a multimeter. The temperature protection switch is normally closed — an open circuit indicates a sensor or lead wire problem.
3. Inspect the sensor wire and connecting wire for damage.
4. Verify all terminal connectors are firmly seated.
5. Disconnect power and use a metal conductor to short-circuit the compressor top head terminal on the main external control panel. If the error disappears after restarting, replace the sensor. If the error persists, replace the main external control panel.

The main external control panel detected a short circuit or open circuit condition on the external temperature sensor.

1. Measure sensor resistance. It should be approximately 15KΩ at 25°C. Check for short circuit or open circuit.
2. Inspect the sensor wire for breaks or damage.
3. Verify all terminal connectors are firmly seated. Check for loose solder joints between the terminal and the main control panel.
4. Check whether the sensor has moisture damage.
5. If no standard sensor is available, swap in a nearby sensor temporarily. If the error clears, replace the original sensor. If the error persists, replace the main external control panel.

All inverter units include voltage inspection circuits (located on the module panel or main external control panel depending on model). When supply voltage drops below 135V or exceeds 275V, the inspection circuit detects over or under voltage and the main external control panel raises this alarm.

1. Check the supply environment while the compressor is running. Normal operating voltage is 198–242V; the minimum guaranteed operating range is 165–265V. If voltage drops by more than 25V after the compressor starts, the supply line has insufficient capacity — advise the user to upgrade the circuit or install a dedicated voltage stabilizer.
2. For outdoor units with PFC panels (without separate rectifier bridges): measure DC voltage between P and N on the module panel while the compressor runs. Voltage should be above 200V. If below this threshold, the reactor may be faulty or the PFC broken.
3. If the compressor is not running but the error is reported and measured supply voltage is above 150V, the voltage inspection circuit itself may be faulty. Identify which control panel hosts the circuit (module panel for two-panel units; external controller for single-panel units) and replace it.

See also: F8

Applies only to models where the module panel is physically separate from the main external control panel. When communication between them is interrupted during operation, this error is raised. Only three components are involved: the module panel, the data connection line, and the main external control panel.

1. Check that the communication connection line (typically a 4-chip connector) between the module panel and main control panel is fully seated and undamaged.
2. Use a multimeter to verify that the main external control panel is delivering correct power to the module panel. Specifically confirm that 5V (or 3.3V) is present at the module panel input.
3. Replace the module panel with a known-good unit. If the error clears on startup, the original module panel is faulty. If the error persists, replace the main external control panel.

See also: F7

The outdoor unit stores operating parameters in an 8-pin EEPROM chip (EE). The main external control panel motor can only run after reading this data. If the data cannot be read, this error is raised. Possible causes: incorrect EE chip data format; damaged EE chip; poor contact of EE chip or fault in the EE reading circuit; EE chip installed backwards.

1. Replace the main external control panel directly.

Applies only to models with electronic expansion valves. The recirculated sensor back temperature is used for electronic expansion valve adjustment and to confirm the four-way valve has changed position during heating. When the main control panel detects an open circuit or short circuit on this sensor, it raises this error.

1. If the error appears in heating mode but not cooling mode, first check whether the four-way valve failed to change position or is experiencing backflow — estimate via high and low pressure readings. For electrical confirmation during heating: verify the four-way valve terminal switches a 220V circuit. If 220V is present but the valve still fails to change position, the four-way valve is faulty. If 220V is absent in heating mode, the main external control panel is faulty.
2. If the four-way valve is not the issue, measure sensor resistance (should be approximately 20KΩ at 25°C). Check for short circuit or open circuit.
3. Verify all terminal connectors are firmly seated. Check for loose solder joints.
4. Check whether the sensor has moisture damage, especially if the sensor lead is routed above the copper pipe.
5. Replace the suspect recirculated sensor with a known-good unit. If the error clears, the original sensor is faulty. If the error persists, replace the main external control panel.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Subdivided failure of F1 (Module Protection Error). See F1 for the full diagnostic procedure.

Three conditions can trigger this alarm: the water storage tank is full; the float switch has opened unexpectedly; or the main control panel is abnormal.

1. Open the drain plug (located at the rear of the unit) and fully drain the water storage tank. Power off and restart to confirm normal operation.
2. If the water level is normal, check the float switch. Confirm the float can move freely and return to its resting position. Use a multimeter to test whether the float switch closes properly in its normal (non-triggered) state. If the switch remains open, replace the float switch.
3. If steps 1 and 2 do not identify the issue, replace the main control panel.

The high-voltage switch has disconnected three times within 20 minutes, either in standby or during operation, triggering this protection.

1. Check that all plug-in terminals are firmly connected and that solder joints to the main control panel are not loose. Gently tug terminals if needed.
2. Use a multimeter to check whether the high-voltage switch is currently disconnected.
3. Use a multimeter to confirm the high-voltage switch is in the normally closed state under normal conditions.
4. If system pressure is normal but the high-voltage switch remains open, the switch itself is faulty.
5. If the pressure switch and connection line are both normal and the failure persists, replace the corresponding main control panel.

System refrigerant level has fallen below 30%, resulting in a loss of cooling capacity and liquid shortage protection.

1. Check the outdoor unit stop valves. Use a hex wrench to turn counterclockwise and confirm valves are fully open.
2. Inspect the evaporator, condenser, and connection pipes for damage or cracks. Pay particular attention to weld points and pipe joints for refrigerant leakage.
3. Use a multimeter to measure both the environmental temperature sensor and the coil temperature sensor at ambient temperature simultaneously. Abnormal resistance on both at the same time may suggest dual sensor failure rather than actual refrigerant loss.

The outdoor coil sensor is detecting excessive temperature. The system is actively reducing compressor frequency to prevent overloading.

1. Check the outdoor coil sensor with a multimeter. Standard resistance is 20KΩ at 25°C.
2. Use a pressure gauge to check system pressure. High pressure may indicate dirty internal blockage or poor external heat transfer, both of which drive up coil temperature.
3. Observe the outdoor fan speed. A slow-running fan reduces heat transfer and raises coil temperature.
4. Use a multimeter to check the voltage-dividing resistance in the outdoor controller's coil sensor circuit. If uncertain, replace the outdoor controller and observe whether the protection clears.

The exhaust sensor has detected that exhaust temperature is too high, triggering a protection shutdown.

1. Check system pressure. Low pressure typically indicates refrigerant shortage, which causes excessive exhaust temperature.
2. Check that indoor and outdoor air inlets are unobstructed. Inspect for dirty evaporator or condenser coils, dirty filters, or blocked inlets — remove any shields if needed.
3. Check indoor air volume at the supply vent. If indoor fan blades are dirty or blocked, clean them.
4. Use a multimeter to measure exhaust sensor resistance at ambient temperature and confirm resistance drift is within normal range.

The indoor coil temperature has risen too high during heating mode, triggering a protection shutdown.

1. Check that the indoor air inlet is unobstructed. Remove any shields or blockages affecting airflow.
2. Check if the filter is dirty. Clean if clogged.
3. Check indoor fan airflow at the supply vent. If the indoor fan is blocked or running slowly, clean it.
4. Use a multimeter to measure the indoor coil sensor resistance at ambient temperature.

The indoor coil temperature has dropped too low during cooling mode, triggering a protection shutdown to prevent the heat exchanger from frosting.

1. Check that the indoor air inlet is unobstructed. Remove any shields or blockages affecting airflow.
2. Check if the filter is dirty. Clean if clogged.
3. Check indoor fan airflow at the supply vent. If the indoor fan is blocked or running slowly, clean it.
4. Use a multimeter to measure the indoor coil sensor resistance at ambient temperature.

The controller has detected AC bus current exceeding the protection threshold and is limiting or reducing compressor frequency.

1. Use a multimeter to check bus voltage. Low supply voltage is a common cause of overcurrent protection.
2. Use a pressure gauge to check system pressure. Excessive pressure may indicate dirty blockage in the system.
3. Replace the outdoor unit controller. If the unit returns to normal, the controller is faulty.

A function protection prompt — not a fault. Indicates the compressor is approaching its power limit and the system is actively reducing frequency to protect it. No alarm is displayed on the indoor unit. If this prompt occurs frequently, investigate supply voltage, module panel, and main external control panel.