Every summer, homeowners from Rogers Park to Beverly, from Pullman to West Garfield Park, and from Oak Lawn, Elmhurst, Hinsdale, Evanston, Skokie, Oak Park, Berwyn, Glenview, Highland Park, and the western suburbs deal with their own version of the same Chicago blues: one part of the house feels fine, while another room feels hot, sticky, and impossible to cool.

Sometimes it is the second floor of a classic Chicago bungalow. Sometimes it is the top unit of a brick two-flat, three-flat, or Greystone. Sometimes it is the upstairs bedroom in a Cape Cod, the second floor of a Georgian, the attic space in an American Foursquare, the back bedroom in a ranch home, or an addition that never seems to cool like the rest of the house.

The homes are different, but the complaints sound familiar: “The AC runs all day.” “The first floor is freezing, but the bedrooms are still hot.” “The top floor never catches up.” “The house feels sticky.” “One room is always uncomfortable.”

Buddy Guy may have made the blues famous in Chicago, but homeowners do not need to live with the summer comfort blues inside their own homes.

The problem is usually not that your air conditioner is too small. More often, the problem is the house the air conditioner is trying to cool.

Chicago has a beautiful housing stock, but many of these homes were built long before today’s comfort expectations, central air systems, smart thermostats, and rising energy costs. The details vary by house style, but the building science is usually the same: air leakage, poor duct performance, attic heat gain, crawlspace or garage exposure, humidity, weak return air, and restricted airflow.

For Chicago bungalows, Cape Cods, Georgians, and American Foursquares, the problem is often attic heat, knee walls, leaky ceiling planes, can lights, attic hatches, and upstairs rooms sitting directly under a hot roof. For ranch homes, the issues often include long duct runs, weak returns, rooms at the far end of the system, attic heat above, or crawlspace and basement conditions below. For two-flats, three-flats, and greystones, the top-floor unit usually takes the biggest hit from roof and attic heat, while lower units may struggle with duct leakage, shared chases, humidity, and air moving between units.

That is why lowering the thermostat usually does not fix the problem. If one part of the home is 8 to 10 degrees warmer than another, the AC may run longer, the cooler rooms may get too cold, and the problem rooms may still feel uncomfortable. In a better-performing home, the difference between rooms or floors should often be much smaller, sometimes as little as 2 degrees.

There are also a few things homeowners can do right away. Open interior doors during the day whenever possible, especially bedroom doors. Keep the HVAC fan circulating air during the active parts of the day. Make sure supply registers and return vents are not covered by beds, rugs, dressers, toys, laundry, or anything else that tends to collect in kids’ rooms. You cannot cool a room properly if the air you pay to cool cannot get into the room or back out.

Start with airflow. Decorative wood floor registers may look nice, but many restrict airflow compared with properly sized metal registers. If a bedroom is already at the end of a duct run, that restriction matters. Keep rugs, beds, curtains, and furniture away from vents. Make sure return vents are open. Do not close multiple vents to “force” air elsewhere. That can raise static pressure, reduce system performance, and make the equipment work harder.