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Kinghome · Heat pump

U3 DC bus voltage drop fault

Medium severity Kinghome KM HT1DIKinghome KM HF1DI

What the control is telling you

The DC bus voltage dropped abnormally.

Applies to: Kinghome KM09HT1DI, KM12HT1DI, KM18HT1DI, KM24HT1DI wall mini-splits; Kinghome KM09HF1DI to KM24HF1DI wall mini-splits (Gree GFH..DA/DB)

Likely causes

  • Unstable supply voltage

Test and repair steps

  1. Check supply voltage.

Models that show this code

9 models in Kinghome KM HT1DI, Kinghome KM HF1DI

KM09HF1DIKM09HT1DIKM12HF1DIKM12HT1DIKM18HF1DIKM18HT1DIKM21HF1DIKM24HF1DIKM24HT1DI

Other codes on the same units

  • P3 Compressor intermediate-frequency test display
  • P5 Compressor phase overcurrent
  • P7 Module temperature sensor circuit fault
  • P8 Power module over-temperature
  • U1 Compressor phase current detection circuit fault
  • U5 Whole-unit current detection fault
  • U7 Four-way valve abnormal
  • EE Memory chip fault

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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. 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.