Musty or moldy odor from vents when American Standard air conditioner runs

Safety first: Turn off power to the indoor unit before cleaning the coil or drain pan.

• Clean evaporator coil: Access the coil and apply an EPA-registered coil cleaner designed to remove biofilm and odors. Follow label directions.
• Clean drain pan and line: Remove standing water, scrub the pan with a mild detergent, and flush the drain line with a vinegar solution to reduce algae.
• Improve filtration: Install a higher-quality filter compatible with your American Standard air handler to reduce dust and spores.
• Consider duct cleaning: If odors persist, have the ductwork inspected and cleaned by a professional, and repair any insulation issues causing condensation.