Line Mini-Split Heat Pump Series
41 codes
/
Fault

E5 Indoor and Outdoor Unit Communication Error

LED

What it means

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.

Special attention When the outdoor unit cannot power on: if the indoor terminal board is not transmitting 220V, replace the main internal control panel. If 220V is present at the outdoor terminal board, check the fuse, reactor, and bridge rectifier. If those are normal, try disconnecting weak-current data wires between control boards — if the main external control panel then initializes successfully, the module panel is likely faulty. If the main external control panel still fails to initialize, replace it.

Inspection path

1 Confirm whether the outdoor unit can power on (indicator lights on then off, relay picks up, PTC does not heat significantly) → 2 Verify indoor and outdoor unit compatibility and wire phase sequence → 3 Connecting wire contact quality → 4 Main internal control panel → 5 Main external control panel

Diagnostic procedure

  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.

Tools

  • Multimeter
  • Main internal control panel in normal working condition

Frequent parts

  • Connecting wire phase sequence and contact
  • Main internal control panel
  • Main external control panel
  • Module panel
Safety Disconnect power at the breaker before opening any access panel. DC bus capacitors retain charge for up to 5 minutes after disconnect — verify with a meter before touching live components.
Sensor Reference 6

Recirculated

20 kΩ @ 25°C
Too-high resistance Incorrect back temperature value affects electronic expansion valve adjustment and four-way valve position confirmation during heating.
Too-low resistance Incorrect back temperature value affects electronic expansion valve adjustment and four-way valve position confirmation during heating.
Triggers FA Recirculated Sensor Error

External temperature

15 kΩ @ 25°C
Too-high resistance Detected outdoor temperature reads lower than actual, causing incorrect temperature-based control decisions.
Too-low resistance Detected outdoor temperature reads higher than actual, causing incorrect temperature-based control decisions.
Triggers F6 External Temperature Sensor Error

Exhaust

50 kΩ @ 25°C
Too-high resistance Detected exhaust temperature reads lower than actual. The system may fail to activate protection when exhaust temperature is genuinely dangerous.
Too-low resistance Detected exhaust temperature reads higher than actual. The unit enters high exhaust temperature protection frequently, compressor frequency threshold rises, leading to unwanted shutdowns. Example: installing a 20KΩ coil sensor in place of the 50KΩ exhaust sensor produces this behavior.
Triggers P5 Exhaust Protection F4 Exhaust Sensor Error

Internal coil

20 kΩ @ 25°C
Too-high resistance Detected temperature reads lower than actual. May cause high-pressure cold-blast protection during heating or frequent anti-freezing protection during cooling.
Too-low resistance Detected temperature reads higher than actual. May cause frequent overheat protection during heating or overload protection during cooling.
Triggers P7 Anti-Freezing Protection in Refrigeration Mode P6 Indoor High Temperature Protection E3 Internal Coil Sensor Error

External coil

20 kΩ @ 25°C
Too-high resistance Detected temperature reads lower than actual. May cause frequent entry into defrost mode, illusory defrost cycles, or protection errors during cooling.
Too-low resistance Detected temperature reads higher than actual. May cause defrost failures during heating or protection activation during cooling.
Triggers P4 Refrigeration Overload Protection E2 External Coil Sensor Error

Internal temperature

15 kΩ @ 25°C
Too-high resistance Detected temperature reads lower than actual. May cause shutdown errors in heating mode or startup failures in cooling mode.
Too-low resistance Detected temperature reads higher than actual. May cause startup errors in heating mode or shutdown failures in cooling mode.
Triggers E1 Internal Temperature Sensor Error