HVACopediaKinghome · Heat pump
F4 Sensor fault (outdoor condenser or discharge)
What the control is telling you
On the wall units F4 is the outdoor condenser sensor. On the Ultranixx units F4 is the compressor discharge sensor. Reading is open or out of range.
Applies to: Kinghome KM09HT1DI, KM12HT1DI, KM18HT1DI, KM24HT1DI wall mini-splits; Kinghome KM09HF1DI to KM24HF1DI wall mini-splits (Gree GFH..DA/DB); Kinghome Ultranixx Eco KD24UHO to KD60UHO outdoor units with KD..UHI air handlers; Kinghome Ultranixx cold-climate KU36UHO and KU60UHO outdoor units with KU..UH2I and KD..UHI air handlers
Likely causes
- Loose sensor plug or poor terminal contact
- Failed (open or shorted) sensor
- Fault in the board's sensing circuit
Test and repair steps
- Check that the condenser/discharge sensor plug is seated fully on the board header.
- Unplug the sensor and measure its resistance; compare it with the temperature/resistance chart in the manual appendix.
- Replace the sensor if the reading is open, shorted or far from the chart.
- If the sensor is good and the plug is secure, replace the control board.
Models that show this code
27 models in Kinghome KM HT1DI, Kinghome KM HF1DI, Kinghome Ultranixx Eco, Kinghome Ultranixx
Other codes on the same units
- F0 Refrigerant recovery mode
- F1 Indoor room temperature sensor fault
- F2 Sensor fault (indoor coil or outdoor condenser)
- F3 Outdoor ambient temperature sensor fault
- F5 Outdoor discharge temperature sensor fault
- F6 Frequency limit for overload / ODU tube sensor fault
- F8 Frequency reduced - overcurrent
- F9 Frequency reduced - high discharge temperature
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Source: Kinghome KM09-12-18-24HT1DI service manual, sec. 9.1 error code list; Kinghome KM09-24HF1DI service manual, sec. 11.1 error code list; Kinghome Ultranixx Eco KD24-60UHO service manual, sec. 3.3-3.4; Kinghome Ultranixx cold-climate KU36/60UHO service manual GC202306, sec. 3.3-3.4. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.