H1 appears on the display and heating stops temporarily.

Note: On many AEG heat pump air conditioners, H1 indicates that the unit is in defrost mode, not a failure.

• Observe behaviour: During H1, the outdoor unit may steam and the indoor fan may slow or stop. This is normal and protects the system.
• Wait for completion: Defrost typically lasts 5–15 minutes, after which normal heating resumes and H1 disappears.
• Check outdoor unit: Ensure the outdoor coil and base are not buried in snow or ice. Clear snow around the unit to allow proper airflow and drainage.
• If H1 is constant and heating never resumes: There may be a sensor or defrost control issue. Have an AEG technician check the outdoor coil sensor and defrost logic.