October 26, 2026 — Austin, TX
Austin’s first real cold front usually arrives in late October or November. That’s when a lot of homeowners switch the thermostat to Heat for the first time since spring and find out the furnace won’t cooperate. Maybe it blows cold air, maybe it runs for a few seconds and quits, or maybe it does nothing at all.
A furnace that has sat in an attic or hall closet through a Central Texas summer has had seven or eight months to collect dust and develop small problems that only show up once it’s asked to work. Here’s what to check yourself, what the common causes are, and when it’s time to call a technician.
Start With the Simple Checks
Plenty of “no heat” calls turn out to be settings or switches. Before you call, take five minutes to go through these:
- Thermostat mode and setpoint. Make sure the thermostat is set to Heat, not Cool or Off, and set a few degrees above the current room temperature. If the screen is blank or dim, replace the batteries.
- Air filter. A clogged filter chokes airflow, and many furnaces will shut themselves off to protect against overheating. If the filter is gray or matted, replace it.
- Furnace power switch. Most furnaces have a switch that looks like an ordinary light switch, mounted on or near the unit. These get bumped off during summer attic trips more often than you’d think.
- Breaker. Check your electrical panel for a tripped breaker labeled furnace, air handler, or HVAC.
- Furnace door panel. A safety switch behind the front panel keeps the furnace from running when the panel isn’t fully seated. If someone changed the filter or looked inside recently, make sure the panel is snapped firmly in place.
- Gas supply. If you have a gas range or water heater, check whether they’re working. If they aren’t, the problem may be the gas supply rather than the furnace.
Common Reasons a Furnace Won’t Heat
If the basics check out, the cause is usually one of these:
- Dirty flame sensor. This is one of the most common first-cold-snap failures. The burners light, run for a few seconds, then shut off, and the furnace may retry several times before locking out. A thin layer of buildup on the sensor keeps it from confirming the flame, so the furnace shuts the gas off as a precaution.
- Failed ignitor. Most modern furnaces use a hot-surface ignitor that glows to light the burners. Ignitors are brittle and wear out over time. If yours is cracked, you’ll hear the furnace start up but the burners never light.
- High-limit switch tripping. When airflow is restricted by a dirty filter, closed or blocked vents, or a weak blower, the furnace overheats and the limit switch shuts the burners down. A furnace that runs in short bursts and blows lukewarm air often points to this.
- Inducer motor or pressure switch problems. Before the burners light, a small fan clears exhaust from the furnace and a pressure switch confirms it’s working. A failing motor, a blocked vent, or a clogged condensate drain on a high-efficiency furnace can stop the start-up sequence cold.
- Control board faults. Most furnaces have a small light on the control board that blinks out an error code. If you can see it through the viewing window, count the blinks and write the number down. That gives the technician a head start.
Homes With Electric Heat Strips
Not every Austin home has a gas furnace. Many have an indoor air handler with electric heat strips, either as the only heat source or as backup for a heat pump. If your system is electric and the air coming out is cold:
- Check the heat strip breaker. Heat strips usually have their own large double-pole breaker, separate from the rest of the system. It can trip while the blower keeps running, so the fan works but the air stays cool.
- Sequencers and relays fail. These parts switch the heat strips on in stages. When one fails, you may get partial heat or none at all. This is a repair for a technician, since the circuits involved carry high voltage.
If your system is a heat pump, the troubleshooting is different. See our guide on what to check when a heat pump is blowing cold air.
Still no heat after the basic checks? Call 512-992-5537. Same-day service is typically available, 7 days a week, across Austin, Round Rock, Pflugerville, and the surrounding area.
The First-Startup Smell: Normal or Not?
A faint burning-dust smell the first time the heat runs each season is normal. Dust that settled on the heat exchanger or heat strips over the summer burns off, and the smell should fade within an hour or so.
Some smells and signs are not normal:
- Rotten-egg or sulfur smell. This can mean a gas leak. Don’t flip switches or try to find the source. Leave the house and call your gas utility or 911 from outside.
- Carbon monoxide alarm sounding. Get everyone out of the house and call 911. Don’t run the furnace again until it has been inspected.
- Burning-plastic or electrical smell that doesn’t fade. Shut the system off at the thermostat and call for service.
When to Stop Troubleshooting and Call
Homeowners can safely handle thermostat settings, filters, switches, and breakers. Anything involving the gas valve, burners, ignition parts, or the electrical components inside the furnace should be left to a licensed technician. That’s especially true if:
- A breaker trips again right after you reset it
- The furnace lights and shuts off over and over
- The error light shows a fault code
- You smell gas or anything burning that doesn’t fade
We test the system, tell you what failed and why, and walk you through the options before any work starts. Our home heating repair service covers gas furnaces, heat strips, and heat pumps, and we service all makes and models.
Prevent the Next No-Heat Call
Many first-cold-snap failures, including dirty flame sensors, weak ignitors, and clogged filters, can be caught during a seasonal check before you need the heat. Our fall furnace and heat pump tune-up guide covers what a good inspection includes, and our maintenance and tune-up service keeps your system ready for whatever the winter brings.
Need Heat Restored?
If your furnace or heat strips aren’t keeping your home warm, call Setpoint Services at 512-992-5537. Same-day service is typically available, 7 days a week. We’re a licensed Texas contractor (TACLA00116720C) serving Austin, Pflugerville, Round Rock, Georgetown, Cedar Park, Leander, Hutto, Taylor, Kyle, Buda, Jarrell, Temple, Belton, and surrounding Austin Area communities.
Setpoint Services — Home AC & Heating Repair serving Austin, TX and surrounding Austin Area communities.
