In which season should a heat pump be set to "cool" mode?

A heat pump should be set to "cool" mode during the summer season when outdoor temperatures rise and cooling is needed for indoor comfort. In this mode, the heat pump operates by extracting heat from the indoor air and transferring it outside, thereby lowering the indoor temperature. This is an essential function as it helps maintain a comfortable living environment during the hottest months of the year.

During winter, a heat pump would typically be set to "heat" mode to provide warmth to the indoor space by transferring heat from the outside (even in cold temperatures) to the inside. In spring and fall, while there may be some cooling needed, the temperatures can often be mild enough that many people still rely on "heat" mode or even just natural ventilation. Thus, the best time to utilize the "cool" mode effectively for a heat pump is in the summer when cooling needs peak.