Troubleshooting A Blocked AC Duct

A blocked AC duct can make it difficult to cool your home as desired. It's important to pinpoint the cause so you can fix the problem.

Signs of a Blocked Duct

Airflow issues are usually very noticeable because a lack of air through the home's duct system means that a room won't cool properly. Blocked ducts typically only affect one or two rooms, so you may notice regular airflow everywhere else in the home, but certain rooms will feel stuffy and overly warm. Sometimes, though, you may have a blockage that affects the airflow to the whole house.

Sometimes, foul odors accompany a blocked duct, either in the affected room or in adjacent areas of the home. Odors can be sickly sweet, similar to rotten meat, or musty mildew odors. These bad smells can provide a clue as to what is causing the blockage.

Common Causes

The most likely cause, particularly if only one or two rooms are affected, is that the ventilation system is blocked. Blockage of AC floor vents, either by closing them or covering them with furniture, is a common cause. Blocked wall air returns, or even an insufficient number of returns, can also be the culprit. If the entire house seems to be suffering from a blocked duct, then there may be issues with the AC filter or filter housing.

Another cause can be an actual blockage in the duct. This will usually only affect one or two rooms. Dead animals, mold buildup, and other debris will sometimes make their way into the ducts and cause a blockage. You may be able to identify the cause if there is an odor. An AC repair tech can also use a camera on a cable to locate the blockage.

Possible Solutions

If vents are closed or blocked, simply open them and rearrange the room so there is plenty of airflow around the vents. If insufficient returns are the problem, your AC repair tech can install additional returns in order to repair airflow. They may also recommend replacing air filters more often and cleaning out the air filter housing so debris doesn't get into the ductwork.

An actual blockage in the duct can be more difficult to address. Your service tech will have to access the duct to remove the blockage. They may also recommend a full duct cleaning, especially if there are lingering odors that need to be addressed.

Contact an air conditioning repair service for more assistance, like Edelman Inc.