The answer to 'ductless system smells bad' is that a smelly ductless HVAC system is often caused by mold, mildew, or bacteria buildup in the unit. This can happen if the system is not properly cleaned and maintained. Symptoms include a musty, unpleasant odor coming from the air vents. The solution is to thoroughly clean the system, including the indoor and outdoor units, coils, and condensate drain line.
If the smell persists or you are unable to fully clean the system yourself, it's best to call a professional HVAC technician. They have the tools and expertise to properly diagnose and resolve the issue. Trying to DIY this type of repair could make the problem worse if the source of the odor is not properly identified and addressed.