Smart thermostat shows E12 and cannot control the cooling (AC) unit via infrared.

Safety first: This is a low-voltage IR control issue; safe to troubleshoot.

• Check line of sight: Ensure the Tado Smart AC Control has a clear line of sight to the AC unit’s IR receiver, typically on the front panel. Avoid placing it behind objects or inside cabinets.
• Distance and angle: Position the Tado device within the recommended distance (usually up to 3–5 m) and roughly facing the AC receiver.
• Clean IR windows: Gently clean the front of the Tado device and the AC receiver window with a soft, dry cloth to remove dust.
• Re-learn remote: In the Tado app, re-run the AC remote setup and ensure the correct model or remote profile is selected. Test basic commands (on/off, temperature up/down).
• Check IR emission: View the front of the Tado device through a smartphone camera while sending a command; you may see a faint flicker from the IR LED. If there is no flicker, the IR LED may be faulty.