If Your AC Struggled During Chattanooga’s Heat Dome, Here’s What It Was Really Telling You

Last week’s heat dome pushed a lot of Chattanooga homes to their limit. Highs near 100° with almost no overnight relief exposed weaknesses that don’t always show up during normal summer days.

Here are the most common complaints we heard — and what they actually meant:

“My unit ran almost nonstop and my electric bill is way up.” When an air conditioner hardly ever cycles off, it’s usually fighting humidity more than temperature. Chattanooga’s high moisture levels during heat waves force systems to work much harder to remove water from the air. Single-stage units often can’t keep up efficiently, so they run constantly and drive up energy use.

“The house still felt humid or clammy even when the AC was running.” This is a classic sign of poor latent load (moisture) removal. In our climate, temperature and humidity are two different jobs. Many systems are decent at lowering the temperature but struggle to pull enough moisture out of the air — especially when it’s already humid outside and the system is running for days straight.

“Certain rooms got hot in the afternoon and we couldn’t keep up.” Uneven temperatures usually point to airflow or capacity issues. It could be undersized equipment, duct leaks losing conditioned air, poor insulation in certain areas, or a system that simply can’t maintain output during peak heat and humidity. Adding a window unit in the living room is a common temporary fix — but it’s also a signal that the main system is falling short.

“What heat wave? Our house stayed comfortable.” On the flip side, some homeowners barely noticed the extreme weather. These are usually homes with well-sized, variable-speed (inverter) systems that ramp up and down instead of turning fully on or off. They handle long stretches of high heat and humidity more efficiently and keep indoor humidity in a comfortable range without running constantly.

What These Symptoms Actually Point To

Most of the issues above come down to how the system handles humidity in addition to temperature — something that becomes obvious fast during a multi-day heat event. Chattanooga’s valley location and high summer moisture make this especially important.

Systems that struggled often have one or more of these limitations:

• Older single-stage equipment

• Incorrect sizing for real-world conditions

• Dirty coils or restricted airflow

• Ductwork issues losing conditioned air

• Inadequate dehumidification capability

What You Should Do Now

If your system showed any of the symptoms above, don’t wait for the next heat wave to address it. A few smart steps right now can prevent bigger problems later:

1. Replace your air filter if it hasn’t been changed recently — pollen and heavy runtime load them up fast.

2. Check your condensate drain for clogs or standing water.

3. Note which rooms struggled the most. This information is useful for a proper evaluation.

4. Schedule a post-heat tune-up. Many systems that ran hard last week will benefit from a professional check right now.

If your AC fought hard just to maintain comfort, it may be time to look at whether a properly sized, variable-speed system would give you better performance and lower bills during the rest of summer — and during the next extreme stretch.