AIRSTAGE Technical Reference
Description of Control Operation
Cooling capacity and compressor frequency control
Applicable models: ASTG30KMTA / ASTG34KMTA / ASTH30KMTD / ASTH34KMTD
The indoor unit monitors the difference between the selected set temperature and the actual room temperature. The inverter then adjusts compressor frequency to match the cooling demand while accounting for outdoor temperature and indoor fan speed.
1. Cooling capacity control
A room temperature thermistor built into the indoor unit continuously monitors the difference between the set temperature and the actual room temperature. The control system uses this information to regulate the compressor operating frequency.
| Room temperature condition | Control response |
|---|---|
| 6.0°C or more above the set temperature | The compressor operates at maximum frequency to provide rapid cooling. |
| Between +6.0°C and -1.0°C relative to the set temperature | Compressor frequency adjusts proportionally according to the detected temperature difference. |
| 1.0°C or more below the set temperature | The compressor stops to prevent overcooling. |
Important: Maximum compressor frequency is also limited by the outdoor temperature and selected indoor fan speed.
2. Compressor frequency range
| Model | Minimum frequency | Maximum frequency |
|---|---|---|
| ASTG30KMTA / 30CMTA | 14 rps | 65 rps |
| ASTG34KMTA / 34CMTA | 16 rps | 77 rps |
3. Frequency limitation based on outdoor temperature
The maximum compressor operating frequency varies according to outdoor conditions. As the outdoor temperature changes, the control system adjusts the allowable frequency ceiling to balance cooling performance and equipment protection.
Frequency order in the table: High / Medium / Low / Quiet fan speed.
| Zone | Outdoor temperature | ASTG30KMTA / 30CMTA max frequency (rps) | ASTG34KMTA / 34CMTA max frequency (rps) |
|---|---|---|---|
| A | 34-36°C | 65 / 45 / 38 / 27 | 77 / 51 / 42 / 29 |
| B | 30-32°C | 65 / 45 / 38 / 27 | 77 / 51 / 42 / 29 |
| C | 21°C | 50 / 38 / 34 / 27 | 70 / 42 / 37 / 29 |
| D | 19-12°C | 38 / 34 / 29 / 20 | 42 / 37 / 34 / 23 |
| E | 10-2°C | 38 / 34 / 29 / 20 | 42 / 37 / 34 / 23 |
| F | 0°C and below | 38 / 34 / 29 / 20 | 42 / 37 / 34 / 23 |
4. Operational summary
- Compressor control: The inverter modulates compressor frequency according to cooling load and outdoor ambient conditions.
- Fan speed and quiet operation: The selected indoor fan mode changes the allowable compressor speed ceiling.
- System protection: Integrated temperature and operating-time controls help prevent short cycling and compressor overrun.
Control diagrams
Technical values are reproduced from the supplied source content. Confirm the applicable service documentation before using these values for diagnosis or field adjustment.