Line Mini-Split Heat Pump Series
41 codes
/
Fault

E8 Communication Failure Between Display Board and Main Control Panel

What it means

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.

Special attention When replacing either the display board or the main internal control panel, confirm they are compatible. If compatibility cannot be confirmed, replace both together.

Inspection path

1 Connection line between display board and main control panel → 2 Display board → 3 Main internal control panel

Diagnostic procedure

  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.

Tools

  • Multimeter
  • Known-good main internal control panel
  • Known-good display board

Frequent parts

  • Main internal control panel
  • Display board
  • Connection line
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