Function 33 – Heating Thermostat-Off Indoor Fan Control
ARTG30LHTA / ARTG36LHTA / ARTG45LHTA / ARTG54LHTA
Correction of intermittent indoor-fan operation time during heating thermostat-off
Function setting 33 changes how the indoor fan behaves in heating mode after the room has reached set temperature and the heating thermostat switches off.
Heating only: This setting manages air circulation and cool-draft complaints while heating demand is satisfied. It does not change normal fan operation while the system is actively heating.
1. Function 33 setting summary
| Setting | Indoor-fan behaviour at heating thermostat-off | Stopping-time cycle |
|---|---|---|
| 33-00 | Standard progressive intermittent operation. The fan periodically circulates air and the stop interval increases while heating demand remains satisfied. | 6 min → 10 min → 17 min |
| 33-01 | Fixed intermittent operation. The fan continues using the same stop interval rather than progressing to longer intervals. | 6 min → no change |
| 33-02 | Shorter intermittent cycle. The fan circulates more frequently. | 4 min → 6 min → 10 min |
| 33-03 | Longer intermittent cycle. The fan remains stopped for longer periods between circulation cycles. | 8 min → 15 min → 27 min |
| 33-04 | Fan stop. The indoor fan stops completely when the heating thermostat is off. | No intermittent circulation |
| 33-05 | Continuous / non-stop operation. The indoor fan continues its thermostat-off fan behaviour. | Factory setting for ARTG LHTA |
Important: Generic function tables may label 00–03 as standard, short and long. For ARTG LHTA, use the detailed stopping-time sequences above.
2. What do the three times mean?
The values are the programmed fan stopping intervals used as the heating thermostat remains satisfied. They are not fan speeds and they are not three settings selected independently.
| 1 | Heating demand is satisfied. The system enters heating thermostat-off control. |
| 2 | The fan stops for the first programmed interval. For 33-00, this is approximately six minutes. |
| 3 | The fan briefly circulates air. This samples room conditions and distributes residual heat. |
| 4 | If demand remains satisfied, the next interval is applied. Depending on the setting, it remains fixed or progresses through the second and third stages. |
The indoor control automatically decides when to move between the programmed intervals. The technician selects only the Function 33 setting.
Example – 33-00
Thermostat OFF → stop about 6 min → brief circulation → stop about 10 min → brief circulation → stop about 17 min
3. Which setting should be used?
| Requirement | Possible setting | Consideration |
|---|---|---|
| No complaint; normal distribution required | 33-05 | Retain factory setting unless there is a specific comfort issue. |
| Cool draft after setpoint is reached | 33-04 | Stops the fan completely; room sensing and temperature distribution may be affected. |
| Reduced fan operation without full stop | 33-00 or 33-03 | 33-03 gives the longest off periods. |
| More frequent room-air sampling | 33-02 | Uses the shortest stop intervals. |
| Consistent intermittent cycle | 33-01 | Maintains an approximately six-minute stop interval. |
Do not use Function 33 to mask another fault. Check room-sensor accuracy, sensor selection, airflow, zoning and short cycling before changing the setting.
4. Adjustment process
| 1 | Stop the air conditioner. |
| 2 | Enter the installer/function-setting menu using the procedure for the fitted controller. |
| 3 | Select Function Number 33. |
| 4 | Select the required value from 00 to 05 and confirm. |
| 5 | Record the original and revised settings. |
| 6 | Isolate power for at least five minutes, then restore power. |
| 7 | Run in heating, allow the unit to reach setpoint and confirm the thermostat-off fan behaviour. |
This article is a practical reference for the ARTG LHTA ducted range. Function availability and factory settings may differ on other indoor-unit families. Always record the original setting and confirm the applicable model documentation before adjustment.