HVACopediaGree · Mini-split · Heating
Heating, defrost, oil return and mode conflict
What happens, in order
- Heating starts when any one indoor unit reaches its heating condition
- Outdoor fan starts 5 s before the compressor and runs high for 40 s; each speed is held at least 80 s
- All indoor units satisfied compressor stops, outdoor fan stops after 1 minute. Some satisfied: compressor reduces frequency immediately
- Heating to cooling, dry or fan compressor stops, 4-way valve de-energizes after 2 minutes, outdoor fan stops after 1 minute
- Defrost compressor stops, all indoor expansion valves open wide, outdoor fan stops 40 s after the compressor, 4-way valve reverses, compressor restarts and climbs to defrost frequency
- Oil return in heating triggered after long low-frequency running; indoor units show H1 and the cycle lasts 5 minutes
- Mode conflict the first indoor unit to run sets the mode; cooling/dry conflicts with heating; fan mode loses to heating, and heating wins whichever unit started first
Timings and thresholds
| Item | Value |
|---|---|
| Outdoor fan high-speed period | 40 s |
| Outdoor fan run-on | 1 min |
| Oil return duration | 5 min |
| 4-way valve change delay | 2 min |
Codes you may see during this
H1
Applies to: Gree Multi21+ multi-zone heat pump outdoor units
Models
More Gree mini-split sequences
- Compressor restart delay and minimum run time · Startup
- Anti-cold-air indoor fan delay · Heating
- Heating mode · Heating
- Heating mode (outdoor logic) and special modes · Heating
- Heating mode and anti-cold-air · Heating
- Cooling and dry mode (multi-zone) · Cooling
- Cooling and dry mode with protections · Cooling
- Cooling mode · Cooling
Related
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Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: Gree Multi21+ multi-zone service manual (MULTI18-24HP230V1CO), Function and Control sections 1 and 2. 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.