Display shows H1 during heating mode; outdoor unit may frost heavily and indoor airflow may stop.

Note: On many Blaupunkt heat pump models, H1 is an informational code indicating the unit is in defrost mode, not a fault.

Steps:

• Observe duration: If H1 appears briefly (5–15 minutes) and then heating resumes, this is normal defrost behavior.
• Check outdoor coil: If the outdoor coil is heavily iced and H1 persists, ensure the coil is clean and that the fan is operating correctly.
• Sensor check: If defrost cycles are too frequent or too long, the outdoor coil sensor may be misreading. Inspect and test the sensor as per earlier sensor procedures.