Great question and one that all of my customers learn the most from. Furnace filter is also your air conditioner filter as well. Think of it as a filter in which it protects both are lungs so we may operate at our maximum capacity and enjoy a healthy life. The furnace and air conditioner are no different, the more air they can consume the healthier life they will live.
Your filter should have a check every month to ensure its not to dirty or any foreign debris got sucked down to the filter through the return air system causing air blockage. Remember this, very important, the more you spend on a filter, the more often it gets changed. Explanation: a more expensive filter will capture more airborne particles making the air much cleaner……in turn, it will need to be changed more often.
Dirty or plugged filters cause a high percentage of service calls and in turn have weakened the motors and the heat exchangers as they have worked harder than normal to pull the air through.
It is an easy job to inspect the filter and change if required, and as I tell my customers a lot cheaper for you to do it than me.
Hint: put a sticky note with a reminder on the backside of your coffee mug and glasses kitchen cupboard door, you will see it more often than if it is on your furnace.
Till next month,