How Can I Fix My HVAC When It Is Not Blowing Hot Air?

You can often fix an HVAC that isn't blowing hot air by checking simple causes like thermostat settings, a clogged filter, or a tripped breaker. The most common issue we see is a dirty filter that makes the furnace overheat and shut the burners off for safety. If basic checks don't help, a technician should test parts like the igniter, flame sensor, blower motor, or heat pump controls; our team handles this daily in the Allerton area.

Try these quick checks before you call:

• Set the thermostat to Heat, Fan Auto, and raise the setpoint 5°F.
• Replace a dirty air filter to restore airflow and prevent limit switch trips.
• Confirm the furnace switch and breaker are on, and the blower door is firmly latched.
• For gas heat, make sure the gas valve is on; if you smell gas, stop and ventilate.

If you ever smell gas or see scorch marks, leave the area and call a professional right away.

Updated: 2026-06-23

Need help in Allerton, IL? Call 217-247-4108 or book online. "Zack and Nick from Lanz were on time and knew what they were doing." — Nathan H.