LineMini-Split Heat Pump Series
41codes
/
Protection

P8Overcurrent Protection

LED

What it means

The controller has detected AC bus current exceeding the protection threshold and is limiting or reducing compressor frequency.

Special attentionThis protection typically occurs under high load conditions. It should not occur at low load or low ambient temperature. Protection priority is ranked after refrigeration overload (P4) and exhaust protection (P5).

Inspection path

1Grid voltage (check for low voltage)→2System pressure (check for blockage)→3Outdoor unit controller

Diagnostic procedure

  1. Use a multimeter to check bus voltage. Low supply voltage is a common cause of overcurrent protection.
  2. Use a pressure gauge to check system pressure. Excessive pressure may indicate dirty blockage in the system.
  3. Replace the outdoor unit controller. If the unit returns to normal, the controller is faulty.

Tools

  • Multimeter
  • Pressure gauge

Frequent parts

  • Grid voltage
  • Outdoor unit controller
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

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

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 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.
TriggersP6Indoor High Temperature ProtectionP7Anti-Freezing Protection in Refrigeration ModeE3Internal Coil 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.
TriggersF4Exhaust Sensor ErrorP5Exhaust Protection

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

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