TJ Mohr of All Comfort Services said sharply lowering a thermostat during extreme heat can backfire because many local air-conditioning systems are built to handle about 90-degree conditions.
Those units may already be running near maximum capacity, so turning the setting way down and then back up can leave the system struggling to catch up.
Mohr also said overly low settings can hurt dehumidification, limiting the unit’s ability to pull moisture from indoor air.
His advice is to keep the thermostat at a temperature that feels comfortable rather than making drastic adjustments during hot weather.