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 a clogged air filter. Symptoms may include the heat pump running constantly but not cooling the home effectively, warm air blowing from the vents, or the unit freezing up.
Some potential solutions you can try yourself include changing the air filter, cleaning the outdoor unit, and ensuring the thermostat is set properly. However, if the problem persists or you're unsure of the cause, it's best to call in a professional HVAC technician to diagnose and repair the issue. They can properly inspect the system, identify the root cause, and make any necessary repairs or adjustments to get your heat pump cooling efficiently again.