What is the purpose of an outdoor unit in an air-to-air heat pump?

The primary purpose of the outdoor unit in an air-to-air heat pump is to dissipate heat and circulate refrigerant. In heating mode, the outdoor unit absorbs heat from the outside air, even at low temperatures, and compresses the refrigerant, which carries this heat into the indoor unit. Conversely, in cooling mode, the outdoor unit expels heat extracted from the indoor environment back to the outside air. This heat exchange is critical for the heat pump's operation, and the effective circulation of refrigerant enables the transfer of energy between the indoor and outdoor environments, ensuring efficient heating or cooling of the space. Overall, the outdoor unit is essential for the heat pump's ability to harness ambient energy and maintain comfortable indoor temperatures.