Diagnosis
The red exclamation mark is the 'No Signal to AC' error. The controller cannot communicate with your air conditioner's indoor unit.
How to Fix It
First, verify the IR blaster is correctly positioned. It must be directly aimed at the AC's IR receiver, typically behind the front panel's right-side plastic. Distance must be under 10 feet with a clear line of sight. Second, ensure the controller is powered. The wall outlet must be live. Third, confirm the AC unit itself has power and is not in a fault state.
If That Didn't Work
The IR code library may be incorrect. Use the Cielo Home app. Navigate to Settings > AC Settings > Change AC. Manually select your AC's brand and model. Perform a 'Test' on the Power button. If the AC does not respond, try selecting a different model from the same brand.
Heads Up
During the 'Change AC' process, the app will prompt you to point the Breez Plus at the AC to 'learn' codes. This step is critical. Ensure the room is quiet and you are within 3 feet of the AC unit.