Dirty filters and coils are two fairly common reasons that a heat pump may not cool an area. A heat pump may fail to cool a building for a variety of reasons, and many causes depend on the exact model and brand as well as the features of the pump.
Filters on the heat pump trap dust and many common allergens, preventing them from cycling through the air in the building. The filters may block the flow of air as they become more and more clogged over time. Replacing dirty filters helps ensure that air flows freely and allows the heat pump to properly circulate air once more. Filters are typically located in either the air duct registers in a room or in a central air-handler cabinet.
The outdoor compressor unit on many heat pump systems is also prone to blockage and contamination. Leaves and dirt can trap heat against the coils of the unit and prevent them from functioning properly. As part of the regular maintenance of the system, users should inspect the coil area of the compressor and remove any contaminants. At the same time, users may also want to ensure that fans and other components are free of debris.