It's often your sense of smell that alerts you when something is amiss with your air conditioner. Most of the time, this isn't especially concerning. A musty smell can indicate mildew, while also suggesting it might be time to have the unit cleaned and generally serviced. A putrid smell can be more disconcerting—not only suggesting that rodents or other vermin may have found their way inside your ducts, but that they may have died while in there. What should you do when the air coming out of your AC unit smells like something is decomposing? 

Hunting for a Rodent 

Even homeowners with a working knowledge of their AC's inner components may be hesitant to hunt for rodents that might be lurking inside—dead or alive. However, it's unlikely that you possess the necessary equipment to do the work. So even if you were inclined to take matters into your own hands, it's preferable to get in touch with a contractor who provides air conditioning services and general maintenance. They'll find the dead rodent and will remove its remains.

Cleaning and Disinfecting

The job isn't done when the contractor locates and removes the dead animal. The location inside the duct where the animal was found will benefit from being cleaned and disinfected. Again, the contractor can handle this for you. It's a matter of hygiene, and you don't want microscopic remnants of an animal's decayed body wafting into the room when the AC is turned on. Disinfection is not only practical but can also give you peace of mind.

Locating the Point of Entry

And of course, preventing the issue from happening again is important. Request a full inspection of the unit, paying particular attention to its external components (such as its outdoor condenser). The point of entry must be identified so that it can be sealed. Any breaches in the ductwork must be repaired, and the unit's external vents and flues may need attention. Blocking vents and flues will prevent the unit from operating (as it will disrupt air intake), but there are specific vent and flue covers that can be fitted (ask your contractor) that don't affect the unit's functionality. 

Nobody wants to deal with vermin inside their home, but at least you can generally just set a trap and wait. However, when the vermin in question have made their way into your AC unit's inner components, you'll need some professional assistance to get rid of them.