Indoor unit frequently turns on and off, room temperature fluctuates widely

Safety: Isolate power before adjusting internal sensors.

• Check sensor location: Ensure the indoor ambient sensor is positioned to sense room air, not directly in the cold supply stream.
• Adjust louvers: Aim the louvers horizontally or slightly upward to avoid blowing directly on the sensor area.
• Verify sensor clip: Confirm the sensor is firmly clipped in its designated holder and not dangling.
• Use appropriate mode: Avoid setting the temperature extremely low or high; use moderate setpoints to reduce cycling.
• If problem persists: A Vaillant technician can evaluate sensor calibration and system sizing.