The answer to 'why is my air conditioner smells bad' is that there are a few common causes, including mold or mildew buildup, a dead animal in the ductwork, or a gas leak. The smell could indicate a more serious issue that requires professional attention.
If the air conditioner has a musty or moldy smell, it's likely due to moisture buildup and microbial growth in the unit or ductwork. This can happen if the condensate drain becomes clogged or the unit isn't properly maintained. Homeowners can try cleaning the unit and replacing air filters, but may need to call an HVAC technician to fully address the issue.