Line Mini-Split Heat Pump Series
41 codes
/
Fault

FA Recirculated Sensor Error

LED

What it means

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.

Inspection path

1 Four-way valve → 2 Recirculated sensor → 3 Sensor wire → 4 Connectors → 5 Main external control panel

Diagnostic procedure

  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.

Tools

  • Multimeter
  • Pressure gauge
  • 20KΩ recirculated sensor in normal working condition

Frequent parts

  • Four-way valve
  • Recirculated sensor
  • Main external 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

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