HVACopediaGree · Mini-split · Heating
Heating mode (outdoor logic) and special modes
What happens, in order
- Heating starts when setpoint minus (room temperature minus compensation) is 1C or more: compressor, outdoor fan and 4-way valve start
- Between -2C and 1C of that difference the unit holds its previous state
- At -2C or lower the compressor stops, the outdoor fan stops 30 s later and the indoor fan blows residual heat
- When switched off or changed out of heating, the 4-way valve is de-energized 2 minutes after the compressor stops
- Outdoor air above 30C stops the compressor immediately and the outdoor fan 30 s later
- Changing from cooling or dry to heating with the compressor running: the 4-way valve energizes after a 2 to 3 minute delay
- Compensation is sent by the indoor unit; if the indoor unit does not send one, the outdoor unit assumes 3C
- Refrigerant recovery indoor unit shows Fo and the outdoor forces cooling at rated frequency; any remote signal exits
- 8C heat mode setpoint 8C, cold-air prevention is disabled, fan speed is automatic
Timings and thresholds
| Item | Value |
|---|---|
| 4-way valve de-energize delay | 2 min after compressor stop |
| 4-way valve energize delay (mode change) | 2-3 min |
| Outdoor fan run-on | 30 s |
| Default compensation | 3C |
| Outdoor air high limit for heating | 30C |
Codes you may see during this
Fo
Applies to: Gree Vireo GEN3 wall mini-split heat pumps 9k-24k
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 and anti-cold-air · Heating
- Heating, defrost, oil return and mode conflict · 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 Vireo GEN3 service manual GREE_VIREOGEN3_SERVICE_090921 (3VIR 9-24k), Function and Control - outdoor unit modes. 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.