Switching AC to heat for the first time each fall is simple as long as you run through a short checklist first: change the filter, confirm your thermostat mode and batteries, clear the vents, and give the outdoor unit some breathing room. Do that before you flip the thermostat over, and you avoid most of the surprises that send Beaumont homeowners searching for heating help on the first cool morning of the year.
Here in the Golden Triangle, this changeover rarely happens on one clean date. Fall fronts move through Southeast Texas in fits and starts, and it’s common to run the air conditioner in the afternoon and the heat overnight during the same week. Knowing what to check ahead of time means your system is ready no matter which mode you need.
Why the Fall Changeover Trips People Up
Most of the year, your HVAC system only has to do one job. In fall, it may be asked to cool, then heat, then cool again within days. If the heating side has been sitting unused since last winter, small issues that went unnoticed can show up right when you need warm air the most.
The good news is that a handful of checks catch nearly everything before it becomes an inconvenient repair call. If you want the fuller pre-fall walkthrough, our guide on how to make fall less scary with an HVAC check-up covers the bigger picture beyond just the changeover.
1. Change or Check the Air Filter
A dirty filter restricts airflow whether your system is heating or cooling. Before the changeover, pull the filter and hold it up to a light. If you can’t see light through it, replace it. A clean filter that matches your blower’s capacity helps your system move air efficiently and reduces strain on the furnace or heat pump as it starts working again.
2. Confirm Thermostat Mode and Settings
Find your thermostat’s mode setting and make sure it’s actually set to heat, not still on cool or off. If your thermostat has an “auto” changeover option that switches between heating and cooling automatically based on the temperature you set, this is a good week to use it, since Southeast Texas days can swing from warm afternoons to chilly nights. If you set specific temperatures over the summer, our summer thermostat settings guide is worth revisiting now that you’re adjusting those numbers for fall.
Battery and Backup Power Check
Many thermostats run on batteries even if they’re wired into your system. A thermostat that dies overnight can leave your heat off during a cold snap. Swap the batteries now, before the first hard freeze, rather than waiting for a failure.
3. Clear Registers and Return Vents
Walk through the house and make sure furniture, rugs, curtains, and boxes aren’t blocking supply registers or return air grilles. Blocked vents force your system to work harder and can create uneven heating from room to room. This is also a good time to vacuum dust off the grilles themselves.
4. Expect (and Understand) the Burn-Off Smell
The first time you run a gas furnace after months of sitting idle, it’s normal to notice a faint burning-dust smell for a few minutes as accumulated dust burns off the heat exchanger. This should fade quickly and not return. If the smell lingers, gets stronger, or smells like something other than dust, turn the system off and call a professional rather than continuing to run it.
When a Smell Means Stop Immediately
Any smell of gas, rotten eggs, or something distinctly chemical is different from a normal burn-off smell. If you ever smell gas in your home, leave immediately, do not operate any switches or thermostats, and call your gas utility or 911 from outside before calling for HVAC service.
5. Give Your Outdoor Unit and Heat Pump Room to Breathe
If you have a heat pump, it works outdoors year-round, including through fall and winter. Clear leaves, grass clippings, pine straw, and any storm debris from around the outdoor unit. Trim back shrubs so there’s open space on all sides. A blocked outdoor unit has to work harder and can struggle to keep up when temperatures drop.
6. Test Every Carbon Monoxide Detector
Gas furnaces, when working properly, are safe, but any combustion appliance carries some carbon monoxide risk if something goes wrong. Test each CO detector in your home the same week you switch to heat, and replace batteries or units as needed. This single step takes a few minutes and gives you an early warning system all winter.
7. Listen and Watch During the First Heating Cycle
The first time your heat runs for the season, stay nearby for a few minutes. Listen for banging, screeching, or rattling that wasn’t there before. Watch for uneven warmth between rooms, weak airflow from vents, or a system that won’t hold the temperature you set. Any of these can point to an issue that’s easier to fix in early fall than in the middle of a hard freeze.
8. Know When It’s Time to Call for a Fall Tune-Up
A visual checklist catches obvious problems, but it can’t test refrigerant levels, inspect electrical connections, or look inside the furnace’s heat exchanger and ductwork. That’s the job of a professional fall tune-up. Thermacon’s Energy Savings Club plan includes a scheduled fall tune-up, along with inspection and cleaning of coils and heat exchangers and priority service scheduling, so small issues get caught before a cold front tests your system for the first time.
9. Take a Quick Look at Insulation and Air Sealing
While you’re checking vents and filters, it’s worth glancing at obvious gaps around doors, windows, and the attic access hatch. Drafts don’t just affect comfort; they make your heating system work harder to hold a temperature, especially during the sharp overnight temperature drops that are common with fall fronts in Southeast Texas. If you notice consistent drafts or rooms that never seem to hold heat, a broader indoor air quality and efficiency assessment can identify where the losses are coming from.
Frequently Asked Questions
How often should I switch between AC and heat in the fall?
In Southeast Texas, it’s common to switch back and forth several times during fall as fronts move through. Using your thermostat’s auto changeover mode, if it has one, can handle this automatically based on the temperature you set.
Should I change my air filter before I switch to heat?
Yes. A fresh filter is the easiest part of the changeover. After a long cooling season the filter is often loaded with dust and pollen, and a clogged filter restricts airflow just as the heating side starts working. Swap it before the first cold front, then check it monthly through the fall.
Do I need to do anything special for a heat pump during the changeover?
Keep the outdoor unit clear of leaves and debris, since a heat pump runs outside in all seasons. Beyond that, a heat pump changeover follows the same checklist as a furnace: filter, thermostat, vents, and a listen-and-watch test on the first cycle.
What if my heat won’t turn on at all?
First check that the thermostat is set to heat mode with a working battery, and that the filter isn’t so clogged the system shut down for airflow protection. If those check out and the system still won’t run, call a professional rather than troubleshooting further on your own.
Should I still run my AC in the fall?
Yes, it’s common in the Golden Triangle to need the air conditioner on warm fall afternoons even after you’ve started using heat at night. Keeping both modes ready to go, including a recent filter change, means you’re never caught off guard either way.
Ready for a Fall Tune-Up Before the First Cold Snap?
Thermacon Service Company has served Beaumont, Port Arthur, and the Golden Triangle since 1980, and our NATE-certified technicians are trained to work on all makes and models. We offer 24/7 emergency service, so if your heat won’t cooperate during a cold front, you’re never left waiting. Call (409) 832-8686 or schedule service online to get your system checked before you need it most.