Symptoms of a Clogged Air Conditioning Filter

An air conditioning filter will only function properly if the air is free to flow through it. If the filter is clogged up, the air conditioning will not work properly, possibly even stopping completely. There are a few symptoms you can look out for, however, to help you recognise whether the filter is clogged or not. 

Reduced Air Flow

If the air conditioning filter is clogged, you will not get as much airflow coming through as you should. Check the air outlets for your conditioning unit to see if they are functioning adequately. 

Dirt in the Duct System

Check the duct system for an accumulation of dust and dirt. If the air filter is clogged, then the duct system will be filled with dirt, which can, in turn, lead to mold spores forming. This can cause allergies. 

Fan Blade Dirt

If the fan blades of your air conditioning system are dirty, this would indicate that the filter is clogged. Clean the blades regularly and look for a build up of dirt that is greater than ordinary household dust. 


Dependent on what your air conditioning filter is clogged with, you may notice an unusual or unpleasant smell in your house. When you turn on your unit, look out for any unfamiliar smells.