Ways To Avoid Overworking Your AC

by | Sep 14, 2021 | AC Maintenance, Air Conditioner, Air Conditioning Maintenance, Maintenance

Wisconsin summers can be horribly hot, and excruciatingly humid. We’ve already had a few really hot spells this summer, and there’s still August and September to get through. You need your AC! This post explores how to avoid overworking your AC so that your whole family can stay cool and comfortable even when Milwaukee is melting.

When central air conditioning is installed, load calculations need to be made. These are based on design criteria like the size of the home in volume, number of windows and other factors.

20 Degree Differential

Your AC should be set to the highest comfortable temperature. The Department of Energy recommends 78 degrees as the best way to balance energy efficiency with comfort. If you decide 78 is too high, remember to keep the 20 degree differential rule in mind. When your AC is set more than 20 degrees below the outside temperature, it’s working harder and longer than it needs to.

Air Flow

Many people believe that shutting off rarely used rooms will help the air conditioning work better. In fact, the opposite is true. AC units are designed with a certain static pressure in mind, so closing and sealing off vents and interior doors add to the unit’s stress and decrease the overall airflow. Doing this can result in resistance and can cause issues with coils leaking, compressor failure, and motors and capacitors failing because the AC unit is working too hard.

Air Filters

A clean air conditioning unit is almost always an efficient one. The key to keeping your air conditioner clean rests primarily with the air filters. The higher efficient five-inch filters that your specific AC manufacturer recommends should be changed every six months. One-inch filters at the unit or the return air grill should be changed a minimum of once a month. If you have an older house or lots of in-and-out traffic, and pets, then those filters likely need to be changed twice a month during the summer season.

Return Air

Air conditioners work by blowing cooled air out into the home, and then recycling that air to cool it again. When the ratio of return air to output air is skewed away from 1:1, your AC becomes much less efficient. Most homes do not have enough return air. If the unit cannot suck back the same amount of air it pushes out, it will start pulling it from cracks and air gaps around the windows, doors and even attics. These areas bring more dust into the house. Evidence of air infiltration is dirt buildup on the floor, window sills, blinds and curtains, and near doors. This is because the AC is pulling air from the outside, a clear sign that there is an issue with return air.


The same sized duct throughout the house is not efficient. It’s essential to look at the volume of space in the room you are trying to cool, which direction it is facing, and how many windows it has. Two rooms of exactly the same size can have different sized ductwork depending on orientation and number of windows. Duct systems should be designed based on a room’s cubic feet per minute (CFM) requirement. That allows you to control dampers and move the air to where it is needed and avoid hot and cold spots. As units get older, they may not be working as efficiently as before. They have a more challenging time maintaining the temperature you have set. Often, ductwork can be the culprit of higher bills. As insulation around the flex duct starts to degrade, the unit has a harder time keeping your house cool.

All of these considerations factor into determining whether or not your AC is overworking. If you are concerned about your air conditioner’s efficiency, contact one of the experts at Quality Heating. We’ll be happy to come out to your home and carry out an assessment with any maintenance required.


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