Improper defrost termination can lead to reduced system performance, increased energy consumption, and potential damage to the heat pump. If the defrost cycle terminates too early, ice may not be fully removed from the outdoor coils, leading to reduced airflow and system capacity. Conversely, if the defrost cycle terminates too late, the system may waste energy and increase operating costs. Proper defrost termination is critical to maintaining optimal system performance and longevity.