Switching From AC to Heat: A Fall Checklist for Houston Homes

Before the first cold front: change the filter, set the thermostat to HEAT 3–5° above room temperature on a mild day, and confirm warm air, normal sounds, and a normal shut-off. Open vents and returns, clear the outdoor unit, and book your fall heating visit early. A brief dusty smell is normal. Electrical or gas smells are not.

Why Houston heaters fail on the first cold night

Your heater has probably been sitting since late winter. Dust settles on heat strips and burners, thermostat batteries run down, and a summer storm can leave a breaker off. Nobody notices, because the AC is doing all the work.

Then a front drops the temperature fast and half of Houston switches to heat the same night. A lot of no-heat calls turn out to be a thermostat setting, a breaker, or a clogged filter. This checklist is how you find those on a mild afternoon instead of at 9 p.m. with the house getting cold. If yours already quit, here is what to do if your heat goes out in a cold snap.

1. Fresh filter

Start here. A filter that loaded up all summer makes the first-heat smell worse and chokes airflow. On electric heat strips, that can mean overheating. Many Houston homes need a new filter every 30–60 days, so if you can’t remember the last change, it’s due. Match the size printed on the frame of the old one.

2. Thermostat to HEAT and a mild-day test run

Pick a mild day before you need heat. Switch the thermostat from COOL to HEAT and set it 3–5° above the current room temperature. Then watch and listen.

• Warm air at the vents once the system gets going
• Normal sounds: no grinding, banging, or loud rattling
• A normal shut-off once the house reaches the setting
• Fresh thermostat batteries, if yours uses them
• Smart thermostats: check that the schedule didn’t revert to “away” or a cooling-only mode

Let it run until it reaches the setting and cycles off. Then set it back to where you want it.

3. Vents, returns, and the outdoor unit

Walk the house. Open any supply registers you closed over the summer, and make sure furniture, rugs, or boxes aren’t blocking the return grilles. If you have a heat pump, the outdoor unit does the heating too. Clear leaves, grass clippings, and anything stacked against it so air can move through the coil.

4. Gas furnace vs. heat pump notes

Gas furnace: test your carbon monoxide alarms and swap their batteries the same day you test the heat. A gas furnace burns fuel and vents through a flue, so a technician should check combustion and the safety controls. That part is not a DIY job.

Heat pump: many Houston heat pumps use electric heat strips as backup on the coldest nights, and those strips are worth a check before the first front. A light frost that clears on its own is part of normal operation. An outdoor unit that’s iced solid needs a technician, not a garden hose.

Not sure which one you have, or weighing a change? Read gas vs. electric heat for Houston homes.

5. The first-heat smell: normal vs. call now

A faint, dusty, slightly burnt smell the first time the heat runs is normal. It’s dust baking off parts that sat all summer, and it should fade within an hour or two of runtime. Crack a window and let it run.

A sharp electrical or melting-plastic smell is not normal. Shut the system off and call. A musty, dirty-socks odor points to moisture on a coil or a drain problem. More on why your heater smells the first time you turn it on.

When to stop and call

Skip the troubleshooting and call us if you see any of these:

• Cold air only, with no heat after the system has been running
• The system won’t start, or starts and shuts right back off
• A breaker trips more than once. Reset it once, not over and over
• A sharp electrical, burning-plastic, or melting smell
• A heat pump outdoor unit that’s iced solid
• Sulfur or rotten-egg smell: leave the house, call the gas utility, then call us

Call (832) 589-0813. Our hours are Monday – Friday 8:00am – 5:00pm, and we accept emergency calls Saturday, Sunday, and after hours.

A fall tune-up, and where Velocity Care fits

This checklist covers what you can see from the hallway. A technician looks at the parts you can’t. If you’d rather not remember to book it every year, Velocity Care seasonal visits put a spring cooling visit and a fall heating visit on a schedule, documented with a photo checklist, with member repair discounts and priority scheduling during normal hours. It’s how we keep your system honest from one season to the next.