Set the thermostat to Heat, not Emergency and not Cool, and put the setpoint a few degrees above the room. Listen. An inducer and then burners is a gas furnace. An outdoor unit that starts is a heat pump. Nothing at all is furnace not turning on or a heat pump that is not heating, depending on which machine you have.
Look at the filter before you need the system. A filter that loaded up through a long cooling season will choke the first heating call. If Emergency Heat is still selected from an old habit, switch it back to Heat unless the outdoor unit will not run. That mode is explained on emergency heat.
A light dusty smell that fades can be dust on a heat exchanger that sat all summer. The longer note is heater smells burning. A rotten-egg smell is not dust. Leave, do not use switches, and call 911 or Southwest Gas. If the system still runs and you want it checked before you depend on it, the visit is a heating tune-up. The printable pass is the season checklist.
What to notice
This is a sorting list, not a price list.
| What you find | What it points to | Next step |
|---|---|---|
| Heat mode, and the furnace lights | The furnace woke up | Let a light dusty smell fade. A tune-up can still be worth doing before you travel. |
| Nothing happens | Thermostat, breaker, door switch, or no call reaching the unit | The furnace-not-turning-on page. One breaker reset, then stop. |
| Outdoor unit stays off and the air is cold | Heat pump not starting, or Emergency Heat left on | Confirm the mode. Then the cold-air page. |
| Rotten-egg smell | Possible gas leak | Leave. No switches. Call 911 or Southwest Gas. Do not wait on this form. |
| You will not be here for the first cold week | A house that has been empty | The snowbird startup page, and a tune-up before you need heat. |
| A faucet is dry, or a garage pipe split | A freeze, not a furnace | Frozen pipes. Shut the main if water is running. |
Name, mobile phone, and ZIP are required. Street address can wait. We follow up the same business day by phone or email. That is a callback, not a promise of a repair the same day.