Derek ColeGM, Simmons One Hour Heating & Air · AI HVAC Answers

AC Won't Cool? Stop The Thermostat Game! #shorts

10 Jul 2026 · 1 min

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1:21

In this short video, Derek Cole explains why an air‑conditioning system struggles when the outdoor temperature is far above its design load. He notes that residential HVAC units are typically sized for a design outdoor temperature of about 95 °F, which only occurs on a few days per year. When the temperature exceeds this design point, the system loses capacity and cannot maintain very low indoor setpoints, especially if you try to cool from 97 °F outside down to 70 °F inside—a 27 °F swing. Cole warns that constantly adjusting the thermostat up and down forces the system to cycle more frequently, making it work harder and reducing efficiency. He advises keeping the thermostat on a consistent schedule or a constant temperature to avoid the “thermostat game.”

Chapters

Give your system a break. If it's 97 outside and you're trying to get it to 70 inside, that's a 27-degree swing. It's working as hard as it can. It is only designed in this state to get to 95 degrees. That is the design temperature of your loads for the homes, is 95 degrees. How often Does it stay 95 degrees? What, maybe, what, 10 days out of, you know, 365? So you size up for 95. If it gets above 95, you start losing capacity and can't quite keep up, and that's fine. But you don't size it for those extreme situations. You size it for normal activity. And one last thing, stop playing the thermostat game. Keep your thermostat at a schedule or a constant temperature. Don't keep going up and down, up and down, up and down with your thermostat. Your system goes on, goes off, goes on, goes off, goes on, goes off. It's having to work harder. Keep your thermostat settings at a constant temperature.