The answer to 'why is my heat pump smells bad' is that a smelly heat pump is often caused by mold, mildew, or bacterial growth in the system. This can happen when moisture builds up in the unit, typically due to poor drainage, leaks, or lack of maintenance.
Some common symptoms of a smelly heat pump include a musty or rotten odor coming from the unit, decreased airflow, and potentially visible mold growth. To fix the issue, you'll need to thoroughly clean and disinfect the system, address any moisture problems, and ensure proper airflow and drainage.