What could cause your heat pump to go into defrost cycle every 5 minutes?

A heat pump may enter a defrost cycle every 5 minutes due to excessive frost accumulation on the outdoor coil, often caused by low outdoor temperatures combined with high humidity levels. Additionally, improper airflow due to blocked filters or dirty coils can lead to inefficient heat exchange, prompting the system to frequently defrost. Faulty sensors or control boards may also trigger unnecessary defrost cycles. Regular maintenance and checks can help identify and resolve these issues.