Cold-Front Heating Readiness and No-Heat Warning Signs

San Antonio winters are usually mild, but a cold front can arrive fast. The time to find out your heat does not work is a mild afternoon in the fall, not the first freezing night. For the short routine checklist, see the winter HVAC checklist.

Test the Heat Before the First Cold Front

Switch the thermostat to heat and run the system for a short test on a mild day. Warm air should reach the vents within a few minutes. A brief dusty smell at first startup can be normal and should fade quickly.

Check the Air Filter

A dirty filter restricts airflow and makes the system work harder. Check it monthly during heavy use and replace it when it looks dirty or on the schedule the filter maker recommends. The size is printed on the frame of the filter you have now.

No-Heat Warning Signs

• Air from the vents that never warms.
• The system starting and stopping every few minutes.
• Burning, electrical or persistent dusty smells.
• Banging, grinding or squealing.
• A heat pump's outdoor unit that stays iced over.
• A thermostat that does not respond.

When to Shut It Off and Get Help

If you smell gas or smoke, see scorching, or a carbon-monoxide alarm sounds, shut the system off if it is safe, get everyone outside, and call the gas utility or 911 as appropriate. Ready.gov advises working carbon-monoxide detectors on every level of the home and never heating a home with a generator, grill or oven.

Vents, Returns and Ducts

Make sure supply vents and return grilles are open and not blocked by furniture or rugs. Rooms that stay much colder than others, or heavy dust around vents, can point to duct problems that need a professional look.

Thermostat Settings

If you have a programmable or smart thermostat, update its schedule for winter. Lowering the setting while you sleep or are away saves energy; follow the thermostat and equipment maker's guidance for your system.