What causes rotten smells from your air conditioner?

Answer by  rathalosslayer (221)

If you have not changed the air filter then that can cause bad smells. Also you must check your ducts to make sure nothing has gotten inside and died and that they are sealed properly so no mold forms. A dirty evaporator coil can also cause rotten smells. Keeping the unit clean and serviced will prevent this.

Answer by  Sherry65 (81)

Mold or mildew inside the drain pan where the evaporator coil is located can cause smells to drift through the air from the air vents. In order to prevent smells, a unit should be serviced at least two times a year. A HVAC company can check proper functioning of the unit and any smells can be addressed at that time.