LineMini-Split Heat Pump Series
41codes
/
Protection

P5Exhaust Protection

What it means

The exhaust sensor has detected that exhaust temperature is too high, triggering a protection shutdown.

Inspection path

1System pressure→2Indoor and outdoor air inlets→3Exhaust sensor→4External control panel

Diagnostic procedure

  1. Check system pressure. Low pressure typically indicates refrigerant shortage, which causes excessive exhaust temperature.
  2. Check that indoor and outdoor air inlets are unobstructed. Inspect for dirty evaporator or condenser coils, dirty filters, or blocked inlets — remove any shields if needed.
  3. Check indoor air volume at the supply vent. If indoor fan blades are dirty or blocked, clean them.
  4. Use a multimeter to measure exhaust sensor resistance at ambient temperature and confirm resistance drift is within normal range.

Tools

  • Multimeter
  • Pressure gauge
  • 50KΩ standard exhaust sensor (25°C)

Frequent parts

  • System refrigerant level
  • Indoor and outdoor air inlets
  • Indoor fan blades
  • Exhaust sensor

Sensors referenced

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