Line Mini-Split Heat Pump Series
41 codes
/
Fault

E3 Internal Coil Sensor Error

LED

What it means

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

Special attention Standard resistance for most inverter model internal coil sensors is 20KΩ at 25°C. Using an incorrect sensor can trigger anti-freezing or overheat protection. A sensor with resistance above 20KΩ reads coil temperature as lower than actual — possible symptoms: high-pressure cold-blast protection during heating or frequent anti-freezing protection during cooling. A sensor with resistance below 20KΩ reads coil temperature as higher than actual — possible symptoms: frequent overheat protection during heating or overload protection during cooling.

Inspection path

1 Sensor → 2 Sensor wire → 3 Connectors → 4 Main internal control panel

Diagnostic procedure

  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.

Tools

  • Multimeter
  • 5KΩ or 20KΩ standard sensor (25°C)

Frequent parts

  • Internal coil sensor
  • Main internal control panel

Sensors referenced

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

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

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 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 P6 Indoor High Temperature Protection P7 Anti-Freezing Protection in Refrigeration Mode E3 Internal Coil 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 F4 Exhaust Sensor Error P5 Exhaust Protection

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

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