LineMini-Split Heat Pump Series
41codes
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Fault

F2PFC Protection Error

LED

What it means

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.

Inspection path

1Supply voltage→2AC and DC power path→3PFC board data wire→4PFC board→5Main external control panel

Diagnostic procedure

  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.

Tools

  • Multimeter
  • PFC board in normal working condition

Frequent parts

  • Supply voltage
  • Reactor
  • PFC board
  • Module panel
  • Main external control panel
SafetyDisconnect 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 Reference6

Recirculated

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

External temperature

15 kΩ @ 25°C
Too-high resistanceDetected outdoor temperature reads lower than actual, causing incorrect temperature-based control decisions.
Too-low resistanceDetected outdoor temperature reads higher than actual, causing incorrect temperature-based control decisions.
TriggersF6External Temperature Sensor Error

Exhaust

50 kΩ @ 25°C
Too-high resistanceDetected exhaust temperature reads lower than actual. The system may fail to activate protection when exhaust temperature is genuinely dangerous.
Too-low resistanceDetected 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.
TriggersP5Exhaust ProtectionF4Exhaust Sensor Error

Internal coil

20 kΩ @ 25°C
Too-high resistanceDetected temperature reads lower than actual. May cause high-pressure cold-blast protection during heating or frequent anti-freezing protection during cooling.
Too-low resistanceDetected temperature reads higher than actual. May cause frequent overheat protection during heating or overload protection during cooling.
TriggersP7Anti-Freezing Protection in Refrigeration ModeP6Indoor High Temperature ProtectionE3Internal Coil Sensor Error

External coil

20 kΩ @ 25°C
Too-high resistanceDetected temperature reads lower than actual. May cause frequent entry into defrost mode, illusory defrost cycles, or protection errors during cooling.
Too-low resistanceDetected temperature reads higher than actual. May cause defrost failures during heating or protection activation during cooling.
TriggersP4Refrigeration Overload ProtectionE2External Coil Sensor Error

Internal temperature

15 kΩ @ 25°C
Too-high resistanceDetected temperature reads lower than actual. May cause shutdown errors in heating mode or startup failures in cooling mode.
Too-low resistanceDetected temperature reads higher than actual. May cause startup errors in heating mode or shutdown failures in cooling mode.
TriggersE1Internal Temperature Sensor Error