Heater Not Working in Las Vegas: What to Check Before You Call

A Las Vegas winter is not a Midwest winter. NOAA’s 1991–2020 normals for the Las Vegas climate station put a typical January afternoon at 58.5°F and a typical January night at 40.5°F. Afternoons often feel fine. Nights, and the hour before work, do not — especially in a house built around summer cooling.

No heat here is usually “the system sat idle for months, then failed on the first cold night,” not a frozen-pipe emergency. It is still worth a straight look. Do the checks below once. If heat does not come back, call during open hours. Do not keep resetting, and do not heat the house with a gas oven. If the furnace starts, runs briefly, then shuts off in a loop, that is furnace short cycling in Las Vegas, not the same as a heater that never lights.

Colton Air Conditioning works these calls across the valley, Monday–Friday, 8am–5pm.

Checks you can do without a phone in your hand

Do them in this order. One pass. Then stop.

1. Thermostat on Heat

Confirm the mode says Heat, not Cool, Off, or Fan. Set the temperature a few degrees above the room temperature on the display. Fan should be Auto unless you meant to run the blower by itself.

A blank screen is often dead batteries. Replace them, then recheck Heat and the setpoint. A schedule can hold an old setpoint and make a working furnace look dead.

If this is a heat pump, leave it on Heat. Do not park it on Emergency Heat or Auxiliary and walk away. That strip heat is a backup, not the normal way a valley heat pump should carry a mild night.

2. Filter

Pull the return filter. Desert dust packs these even when the heater barely ran, because the same blower moved cooling air most of the year. If the filter is gray, collapsed, or sucking in against the grille, replace it with the size printed on the frame.

A loaded filter is a common reason a furnace lights, gets hot, and then shuts off. One new filter is a fair test. A second filter the same hour will not fix a failed part.

3. One breaker reset

Find the breaker marked furnace, air handler, or heater. If it is tripped, reset it once. If it trips again right away, leave it off.

Also look at the switch on or next to the furnace. It looks like a light switch and it kills power to the cabinet. People bump it off while storing holiday bins. Flip it on only if you did not shut it off for a burning smell.

4. Furnace switch, then listen once

With the thermostat calling for Heat and the switch on, stand by a supply register for a few minutes. You want airflow that is actually warm, not just the blower.

A gas furnace may run a draft fan, pause, and then light. If it tries and quits, or the blower runs and the air stays room temperature, the safe homeowner steps are finished. Ignitors, flame sensors, pressure switches, and boards are a diagnosis, not a second reset.

5. Shut it off if you smell burning

A short dusty smell the first time the heater runs for the season can be dust on a heat exchanger that sat all summer. It should fade.

Shut the system off — furnace switch, then the breaker if you can do it safely — if:

• the smell stays or gets stronger
• it smells like electrical insulation or hot plastic, not light dust
• you see smoke, scorched wire, or a panel that was already loose
• the breaker tripped and you already reset it once

Leave it off. A burning smell is not a filter problem and not something to “try again later.”

If a carbon monoxide alarm sounds, leave

Carbon monoxide from a gas or oil furnace is invisible and has no odor. The CDC lists headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion — often described as flu-like — as the common symptoms.

If the alarm sounds, or anyone in the house has those symptoms and you suspect the heater:

1. Get everyone, including pets, outside to fresh air.
2. Call 911 from outside. Do not stay in to find the source.
3. Do not go back in until emergency responders say you can.
4. Do not run that appliance again until a qualified tech has checked it.

A CO alarm is not a callback item for the next business morning. The CDC also says to have a fuel-burning heating system serviced every year, and to keep CO alarms near every sleeping area. The CPSC says an alarm is not a substitute for that service.

Do not heat the house with a gas oven, a grill, or any unvented fuel heater. A plug-in electric space heater, used the way its label says and kept clear of anything that can burn, can hold one room until the system is looked at during open hours.

What those checks usually ruled out

We do not price a new furnace from that table. A dirty flame sensor or a failed ignitor is a repair conversation. A cracked heat exchanger, a repeated electrical failure, or a unit that is already at the end of its life is a different one — the same repair-or-replace judgment we use in repair or replace an old system, not a scare quote because the bedroom was cold. If another company already told you the only option is replacement, a second look is reasonable: HVAC second opinion.

West of I-15, many furnaces sit in the attic, so the first cold night is also the first time that cabinet has been asked to heat air through ducts that only moved cooling all summer. Start with the checks above before anyone climbs into the attic.

When to call, and when we can answer

Call Colton when the checks are done and you still have no heat, the breaker trips again, the burn smell is real, water is showing up at the air handler, or a CO alarm already sent you outside and the fire department has cleared the house.

Have ready if you can: neighborhood, gas furnace or heat pump, about how old the equipment is, and the symptom in plain words (“blower on, air cold,” “clicks and quits,” “breaker will not stay on”).

Hours are Monday–Friday, 8am–5pm. That is the window we schedule heater calls. If the house is cold outside those hours, use the checks and the safety steps above, and call when we are open. We will tell you whether we can see it and what to leave off.

FAQ

Why does no heat matter if January afternoons are in the upper 50s?

Because the cold is overnight. A normal January low in Las Vegas is 40.5°F, and a lot of houses lose heat quickly once the sun is down. You can be comfortable at 4pm and cold by 6am with a heater that never actually lit.

I set the thermostat to Heat and still get nothing. What now?

Batteries, a schedule, the filter, one breaker reset, and the furnace switch. Then listen once for warm air. If the cabinet tries and shuts down, more resets will not finish the diagnosis.

How many times can I reset the breaker?

Once. An immediate second trip means leave it off. Resetting it in a loop is how a small electrical fault becomes a damaged board or a worse short.

The heater smells on the first cold night. Is that normal?

A light dusty smell that fades can be a season’s dust burning off. A smell that stays, any electrical smell, or any smoke is a shut-off. Leave the furnace switch off.

The carbon monoxide alarm went off. Should I call HVAC first?

No. Get outside and call 911. HVAC comes after responders have cleared the house and told you it is safe to return. Do not restart the heater to “see if it does it again.”

Does no heat mean the furnace has to be replaced?

No. Many no-heat calls are a sensor, an ignitor, a filter, a switch, or a thermostat. Replacement is for equipment that fails the repair-or-replace test after someone has actually measured and looked — not because the first night of the season was inconvenient.

What hours can I reach Colton?

Monday through Friday, 8am to 5pm. We do not keep a night window for heater calls.

No heat after the checks above? Call Colton Air Conditioning at (702) 738-6976 Monday–Friday, 8am–5pm. Tell us the symptom and what you already tried. We will tell you if we can see it and what to leave off.

If we have already fixed the heat and the house is right again, a short note helps the next Las Vegas homeowner: Leave a Google review.

Colton Air Conditioning · Las Vegas Valley residential HVAC · Monday–Friday 8am–5pm

Sources

• NOAA National Centers for Environmental Information, 1991–2020 monthly normals, station USW00023169 (Las Vegas). January normal maximum 58.5°F, minimum 40.5°F. Accessed 2026-10-02: https://www.ncei.noaa.gov/access/services/data/v1?dataset=normals-monthly-1991-2020&stations=USW00023169&dataTypes=MLY-TMIN-NORMAL,MLY-TMAX-NORMAL,MLY-TAVG-NORMAL&format=json
• National Weather Service Las Vegas, 1991–2020 climate normals overview (NCEI is the official normals source): https://www.weather.gov/vef/1991-2020Normals
• CDC, Carbon Monoxide Poisoning Basics (symptoms, furnaces as a source, annual heating service, alarms near sleeping areas, do not heat with a gas oven): https://www.cdc.gov/carbon-monoxide/about/index.html
• CDC, Furnace Safety Fact Sheet (gas- and oil-burning furnaces produce CO; CO is invisible and odorless): https://www.cdc.gov/carbon-monoxide/factsheets/furnace-safety-fact-sheet.html
• CPSC, Carbon Monoxide Questions and Answers (alarm response: leave, call 911, do not re-enter or restart the appliance until checked): https://www.cpsc.gov/Safety-Education/Safety-Education-Centers/Carbon-Monoxide-Information-Center/Carbon-Monoxide-Questions-and-Answers

Call (702) 738-6976 or Book Online. License 0092120. Hours Monday through Friday, 8am to 5pm. Saturday and Sunday are closed.