Preventative maint. of your Air conditioning unit is worth every penny. We just had our condenser coil cleaned. If you smell a house that is musty or moldy when the a/c is on then get the condenser coil cleaned by a proffesional. The past week and a half when the a/c was on I couldn't stand the smell and then finally turned off for two days and had it cleaned today took two hours and now no smell. I learned that there is a UV light that can be put up there to hinder any future mold growth in addition to after the chemical is applied and drained and washed away. and keep your filters clean. and look into UV light.