The answer to 'why is my heat pump not cooling' is that there could be several common causes, such as a refrigerant leak, a problem with the compressor, or issues with the airflow. Symptoms may include warm air coming from the vents, the system running continuously, or the unit freezing up.
Some potential solutions include checking the air filters, clearing any blockages around the outdoor unit, and ensuring the thermostat is set properly. However, if the issue persists, it's best to call a professional HVAC technician to diagnose and repair the problem, as they have the expertise and tools to properly identify and fix the issue.