By Commercial Service Company · October 20, 2026
A gas-fired rooftop unit that won't heat is one of the more common cold-weather calls we get around Conway, Little Rock, and the rest of central Arkansas. Before you assume the worst, there are a few simple things worth checking. But once you're past the thermostat and the filter, gas heat troubleshooting is a licensed technician's job every time — for good reason.
What You Can Safely Check First
Before calling for service, it's worth ruling out the easy stuff. These checks don't involve opening any gas or electrical components and are safe for an owner or manager to do.
- Thermostat settings. Confirm it's set to "heat," not "cool" or "off," and that the set temperature is actually above the current room temperature. A programmed schedule or a thermostat with dead batteries can quietly cause a lot of "no heat" calls.
- Air filter. A badly clogged filter restricts airflow and can cause the unit's safety controls to shut the heating cycle down before it ever gets going. Check it, and replace it if it's dirty.
- Breaker and disconnect. Rooftop units typically have a disconnect switch near the unit and a breaker in the electrical panel. Confirm neither has been tripped or accidentally switched off. If a breaker trips repeatedly after you reset it, stop — that's a sign of an electrical problem and not something to keep resetting on your own.
- Vents and registers. Make sure supply and return vents inside the building aren't blocked by boxes, furniture, or merchandise. Restricted airflow stresses the system and can trigger shutdowns.
If you've checked all of this and the unit still isn't producing heat, it's time to call a technician rather than keep guessing.
Why Gas Components Are Always a Technician's Job
Once the issue is anything beyond the thermostat, filter, or breaker, it moves into territory that requires training, proper test equipment, and licensing. This isn't about making the call sound more complicated than it is — gas heat sections involve real safety risks if handled incorrectly, including gas leaks, improper combustion, and carbon monoxide concerns. A licensed technician is equipped to diagnose and correct these issues safely. Common culprits a tech will check include:
- Ignition system problems. Hot surface igniters, pilot assemblies, or electronic ignition modules can fail and prevent the burner from lighting at all.
- Flame sensor issues. If the unit lights briefly and then shuts off, a dirty or failing flame sensor is often the cause — it's a safety device, and it's doing its job by shutting things down when it can't verify a flame.
- Gas valve or gas supply issues. A gas valve that won't open, or a supply problem upstream of the unit, will stop heat production cold. Diagnosing this safely requires the right tools and training.
- Limit switches and safety controls. Rooftop units have multiple safety switches that shut down the heating cycle if something isn't right — airflow, temperature, or pressure related. These exist to prevent damage or worse, and a technician needs to find out why one tripped rather than just resetting it.
- Control board faults. Modern RTUs rely on a control board to sequence ignition, blower operation, and safety checks. A faulty board can mimic several other problems and takes diagnostic experience to isolate correctly.
Trying to bypass a safety switch or work on gas or electrical components without the proper training isn't a shortcut — it's a real hazard to people and equipment, and it's never something we'd recommend to an owner.
Why Rooftop Heat Problems Often Show Up Suddenly
Rooftop units sit outside year-round, exposed to Arkansas heat, humidity, and winter cold swings. Components that worked fine all summer running the cooling side can fail the first time the heat section fires up for the season. That's why a lot of "no heat" calls cluster right when the weather turns — it's often the first real test those components have had in months.
Keeping Your Building Heated Reliably
Routine maintenance before heating season — checking ignition components, safety switches, and the gas train while things are still working — catches a lot of these issues before they leave a building cold on a Monday morning. If your rooftop unit's heat isn't working, or you want it inspected before the season fully turns, Commercial Service Company has served central Arkansas businesses since 1976, covering Little Rock, Conway, Benton, Bryant, Maumelle, Jacksonville, Searcy, and Russellville. Give us a call at 501-548-2374 and we'll get a technician out to diagnose it safely.