In Tucson the heat sits unused for most of the year. Then the first cold night arrives, everyone turns the thermostat up at the same time, and a lot of systems that have been idle since spring do not start the way they should.

Before you book a repair, a few simple checks can save you a service call. These are safe for any homeowner and take about 15 minutes.

1. Check the thermostat first

It sounds obvious, but it is the most common cause. Make sure the thermostat is set to Heat, not Cool or Off, and that the set temperature is a few degrees above the room temperature. If the screen is blank or dim, replace the batteries. If you have a programmable or smart thermostat, check that a schedule or eco mode is not holding the temperature down.

2. Look at the breaker panel

Your heating system has its own breaker, and heat pumps and electric furnaces often have two (one for the indoor unit and one for the outdoor unit). If a breaker has tripped, switch it fully off and back on once. If it trips again, leave it off and call a technician. A breaker that keeps tripping is a sign of an electrical problem.

3. Find the furnace switch

Most furnaces and air handlers have a service switch nearby that looks exactly like a light switch. It is easy to flip off by accident, especially in a closet, garage or attic. Make sure it is on.

4. Replace the air filter

After a dusty summer, many filters are overdue. A clogged filter chokes airflow, and modern furnaces will shut themselves off to protect against overheating when the air cannot move. Put in a fresh filter and try again.

5. Make sure the furnace door is closed

Furnaces have a safety switch behind the front panel. If the door was removed to change the filter and not pushed back in all the way, the system will not start. Press it firmly back into place.

6. Check vents and returns

Open the supply vents and make sure furniture, rugs or curtains are not covering the return grilles. Closing too many vents to save energy can make the system overheat and shut off.

7. Heat pump? Know what defrost looks like

Many Tucson homes heat with a heat pump. On cold mornings, the outdoor unit can build up frost and will run a short defrost cycle to clear it. During defrost you may see steam rising from the outdoor unit and feel cooler air from the vents for a few minutes. That is normal.

What is not normal: cold air for a long time, a house that never warms up, or an outdoor unit that stays covered in ice. If you have an emergency heat setting, it can keep you warm for a short time, but it uses backup heat strips that cost more to run, so call for service rather than leaving it on for days.

8. Gas furnace? Watch the startup

When a gas furnace starts, you should hear the inducer fan, then the igniter, then the burners light. If the burners light and then shut off after a few seconds, the flame sensor is often dirty. That is one of the most common heating repairs after the summer, and it is a job for a technician, not a DIY fix.

A faint burning smell for a few minutes on the first run of the season is normal, as dust burns off. A smell that does not go away is not.

Safety first: when to stop and call

  • You smell gas (a rotten-egg smell): do not touch switches or the thermostat. Leave the house and call Southwest Gas or 911 from outside.
  • Your carbon monoxide alarm sounds: get everyone outside and call 911. Then have the furnace inspected before you use it again.
  • A breaker trips again after you reset it once.
  • Burning, electrical or plastic smells that do not fade.
  • Banging, grinding or screeching noises.

How to avoid a no-heat night

The easiest fix is to test your heat in October, on a warm afternoon, before you actually need it. A fall maintenance visit catches a weak igniter, a dirty flame sensor or a failing capacitor before the cold weather does. The Cowboy Comfort Plan starts from $175 and includes two visits a year, one before summer and one before winter. Read our fall maintenance checklist for more.

Still no heat? We can help

Arctic Cowboy repairs gas furnaces, heat pumps, air handlers and thermostats across Tucson and Southern Arizona, with 24/7 service for urgent problems. We are a family-owned company run by Brandon and Kelly Sill, licensed, bonded and insured (AZ ROC #359497), and rated 5.0 across more than 130 Google reviews. Call or text 520-633-9931 or see our heating repair service.