“No heat” on this page means the house is cold and you want the request sorted that way. It does not mean a truck is rolling, and it does not mean a night desk is staffed. The form asks for a callback. A licensed contractor sets any visit after they contact you. The page that sorts a furnace from a heat pump, once the house is safe, is heating repair.
Leave the house for these two
A rotten-egg gas smell is not a form question. Leave, do not flip switches, and do not light anything. Southwest Gas’s site says to call 911 and Southwest Gas at 877-860-6020 if you suspect a leak, whether or not you are a customer. That instruction is on swgas.com, read October 19, 2026. Send this form only after you are outside and the utility has been called.
A carbon monoxide alarm is the same kind of stop. Get people and pets outside and call 911 from outside. After the house is clear, the longer explanation is carbon monoxide and a Tucson heater. Do not air the house out and go back in to see if the alarm was “just the furnace.”
What to check if the air is only cold
If there is no gas smell and no alarm, three notes help the callback. First, the thermostat: Heat, not Cool, and not a setting labeled Emergency. Emergency Heat on many heat-pump thermostats locks out the compressor. That distinction is on heat pump emergency heat. Write down the exact word on the display.
Second, the equipment. A gas furnace that clicks, the fan starts, and then nothing is a furnace sequence. The page for that pattern is furnace not turning on. An outdoor unit that should start in heat and does not, or that blows cool air from the vents, is a heat pump sequence. Those pages are heat pump repair and heat pump blowing cold air.
Third, the simple items you can see without opening a panel. A filter you cannot see through. A breaker that is off: try it once, and leave it off if it trips again. A thermostat with a blank screen may need batteries. Do not remove the furnace doors, and do not light a pilot. A burning smell that is not gas is discussed on heater smells burning. A pipe that split, or a faucet that went dry, is frozen pipes, not a furnace symptom.
What to tell the contractor
Gas furnace, heat pump, or you are not sure. Whether the outdoor unit is running. The word on the thermostat. Whether any air is moving at the vents. About how cold the house is. Whether anyone smelled gas, and that you already left and called. A photo of the thermostat is enough. The model number can wait. Choose No heat on the form, and System down now if the house is cold now. That sorts the request. It does not put a technician in the driveway.
If the heater still runs and you want it checked before the next cold morning, that is a heating tune-up or the first cold night checklist, not this page. Repair versus a new furnace, with HomeAdvisor’s national range, is furnace replacement cost.