September 17, 2026
September in Lexington, SC, can be a confusing time for your HVAC system. Summer may technically be winding down, but South Carolina weather doesn’t always get the memo. You may wake up to a cool morning, turn the air conditioner on by mid-afternoon, and then find yourself reaching for a blanket again that evening. These temperature swings are common during the transition from summer to fall, but constantly changing between heating and cooling can leave homeowners wondering how they should be using their HVAC system. Here are a few ways to stay comfortable as Lexington moves from summer heat into cooler fall weather. Is It Okay to Switch Between AC and Heat? Yes. Modern HVAC systems are designed to provide both heating and cooling as needed, so switching between the two during unpredictable fall weather isn’t necessarily a problem. However, it’s a good idea to give your system a few minutes after turning off one mode before switching to the other. Rapidly changing the thermostat back and forth can put unnecessary stress on the system. If your home is comfortable without heating or cooling, you can also turn the system off and take advantage of the milder weather. Don't Overreact to Cool Mornings One of the biggest challenges during early fall in Lexington is the difference between morning and afternoon temperatures. If you wake up to a chilly house, you may be tempted to immediately turn up the heat. But if warmer temperatures are expected later in the day, your home may naturally warm up without much help from your heating system. Instead of making big thermostat adjustments, try making smaller changes and allowing your home some time to respond. Take Advantage of Cooler Weather Early fall is one of the few times of year in South Carolina when your HVAC system may get a break. On comfortable days, opening windows can bring fresh air into your home without relying on your AC. Just remember that outdoor humidity and allergens can still be an issue, so keeping the windows closed may be a better option on particularly humid or high-pollen days. Ceiling fans can also help keep air circulating when it's not quite warm enough to justify turning on the air conditioner. Pay Attention the First Time You Turn on the Heat Even if daytime temperatures are still warm, cooler nights are coming. When you turn on your heating system for the first time this season, pay attention to how it performs. You may notice a slight dusty or burning smell during the first heating cycle as dust that settled during the summer burns off. This should typically disappear fairly quickly. However, persistent burning or electrical odors, unusual noises, weak airflow, or a system that isn't producing warm air are all reasons to have your HVAC system checked by a professional. It's much better to discover a heating problem during a mild September evening than during the first genuinely cold night of the season. Check Your Thermostat Settings Your thermostat can make the transition between seasons much easier. If you have a programmable or smart thermostat, review your schedule and temperature settings now. The settings that worked during July and August may no longer make sense as the days become shorter and outdoor temperatures begin to change. Some thermostats also have an "auto" mode that can automatically switch between heating and cooling based on the temperatures you've selected. If you're unsure how to use this feature correctly, an HVAC professional can help you determine the best settings for your home and equipment. Don't Ignore Comfort Problems During Mild Weather Because September weather can be relatively comfortable, it can be easy to overlook HVAC issues. Maybe one room isn't cooling as well as it did earlier in the summer. Perhaps you've noticed an unusual noise, weaker airflow, or your system seems to be running longer than usual. Those small issues are worth addressing before your system transitions into regular heating use. Mild weather gives you an opportunity to take care of problems before you truly depend on your heat. Get Ready for Fall in Lexington, SC Fall in Lexington doesn't always arrive all at once. We can still have plenty of warm afternoons mixed with cooler mornings and evenings, which means your HVAC system needs to be ready for both. If your system isn't keeping your home comfortable, you're having trouble switching between heating and cooling, or something simply doesn't seem right, Brian's Heating & Cooling is here to help. Our experienced team serves homeowners throughout Lexington, SC, and the surrounding Midlands with reliable heating and cooling service, maintenance, and repairs. Call Brian's Heating & Cooling today at 803-796-1788 to schedule HVAC service and make sure your home is ready for whatever South Carolina's fall weather brings.