Residential Air-to-Air Heat Pumps Practice Exam – Prep & Study Guide

During the defrost mode in an air-to-air heat pump, the superheated refrigerant flows from the compressor to the outdoor coil. This is a critical process because the purpose of the defrost mode is to remove frost or ice that may have accumulated on the outdoor coil, which can impede the heat pump's ability to efficiently extract heat from the outside air.

In this scenario, the superheated refrigerant entering the outdoor coil helps to raise the temperature of the coil, causing the frost or ice to melt. This is essential for ensuring that the heat pump continues to function efficiently and effectively by maintaining proper airflow and heat exchange.

The flow of the refrigerant to the outdoor coil during defrost distinguishes this process from regular heating or cooling modes, where the refrigerant would typically cycle differently through the system. Understanding this helps clarify the unique operational requirements of a heat pump, particularly in colder weather conditions.