HVACopediaKinghome · Heat pump · Defrost
Defrost and oil return
What happens, in order
- In heating, defrost starts when the outdoor coil sensor reaches the preset defrost temperature
- 4-way valve switches to the cooling position and the outdoor fan stops
- Defrost ends when the coil sensor reaches the preset stop temperature
- 4-way valve returns to heating, then compressor and outdoor fan restart
- Dip switch selects standard (default) or strong defrost; strong defrost runs longer for very cold conditions (switch 1 on the Eco outdoor board, switch 2 on the cold-climate board)
- Oil return after long low-frequency running the compressor is raised to an oil-return frequency for about 5 minutes
- Forced defrost (cold-climate board) hold SW1 about 5 s, short-press SW1 to function 06, press SW2 or SW3 to set ON, press SW1 to save; the menu exits after 10 s idle
Timings and thresholds
| Item | Value |
|---|---|
| Oil return duration | About 5 min |
| Menu idle timeout | 10 s |
| SW1 hold to enter debug | About 5 s |
Applies to: Kinghome Ultranixx ducted heat pump condensing units with air handlers
Models
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Source: Kinghome Ultranixx Eco KD24-60UHO outdoor + KD..UHI air handlers service manual, 2.1-2.3 Operation mode and control; Kinghome Ultranixx cold-climate ducted heat pump KU36UHO-KU60UHO service manual GC202306, 2.1-2.3. Written in our own words; timings can differ by model and software version, so check the manual for your exact unit.
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.