| 21 | Absence of extraction flow (FF). | The extractor does not generate sufficient depression (motor stopped, turbine dirty or seized), so the pressure switch does not activate. Check that voltage is reaching the extractor and measure ΔP at the pressure switch or the rpm signal: if with the extractor powered there is no depression/return, the fan is defective. |
| 23 | Low extractor fan speed (FF). | The extractor rotates below the setpoint (e.g., <800 rpm) due to wear/bearings, winding, or dirt in the turbine. Verify by reading the speed sensor signal (tacho) or measuring the motor's rpm/voltage and consumption. |
| 24 | Extractor operation control fault (FF). | The PCB does not receive feedback from the extractor speed sensor (Hall sensor/tachometer or the fan's own wiring). Check the continuity of the tach wire and the presence of pulses (approximately 5–12 V) when rotating; if there is no signal with the motor powered, the extractor is faulty. |
| E21 | Absence of extraction flow. | The extractor does not create the required flue gas flow, so the pressure switch threshold is not reached. Check power supply to the motor and pressure in the pressure switch; if there is no ΔP with voltage present, the fan (extractor) is faulty. |
| E23 | Low fan speed. | The extractor rotates below the theoretical speed (stiff bearings, dirty rotor, or motor fault). Check the fan's rpm reading/tacho signal and electrical consumption; if the speed is low with correct voltage, the extractor is defective. |
| E24 | Extractor operation control fault. | The PCB does not detect the return signal from the speed sensor of the extractor itself (internal sensor or its wiring). Check continuity and pulses of the tachometer wire to the PCB; absence of signal with the motor running indicates a fault with the fan. |
