Line Mini-Split Heat Pump Series
41 codes
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Fault

F7 OVP or UVP Error (Over/Under Voltage Protection)

LED

What it means

All inverter units include voltage inspection circuits (located on the module panel or main external control panel depending on model). When supply voltage drops below 135V or exceeds 275V, the inspection circuit detects over or under voltage and the main external control panel raises this alarm.

Special attention On some models, the OVP/UVP signal is transmitted through the connector between the module panel and main external control panel. A poor connection here may cause the signal to fail to transmit, resulting in a false alarm that may eventually resolve as F8 (module-to-controller communication error). Note this distinction during diagnosis.

Inspection path

1 Supply voltage → 2 Internal DC voltage → 3 Reactor wiring → 4 Module panel → 5 Main external control panel

Diagnostic procedure

  1. Check the supply environment while the compressor is running. Normal operating voltage is 198–242V; the minimum guaranteed operating range is 165–265V. If voltage drops by more than 25V after the compressor starts, the supply line has insufficient capacity — advise the user to upgrade the circuit or install a dedicated voltage stabilizer.
  2. For outdoor units with PFC panels (without separate rectifier bridges): measure DC voltage between P and N on the module panel while the compressor runs. Voltage should be above 200V. If below this threshold, the reactor may be faulty or the PFC broken.
  3. If the compressor is not running but the error is reported and measured supply voltage is above 150V, the voltage inspection circuit itself may be faulty. Identify which control panel hosts the circuit (module panel for two-panel units; external controller for single-panel units) and replace it.

Tools

  • Multimeter

Frequent parts

  • Supply voltage
  • Reactor
  • Module panel
  • Main external control panel

Related codes

F8 Main External Control Panel and Module Panel Communication Error
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