furnace repair

Tucson is Getting Cold, but My Furnace Wont Turn On

Figuring out a furnace-related problem might feel like an overwhelming task when your heat won’t work. But it doesn’t have to be like that.

There are a few quick, inexpensive fixes you can do on your own to skip a furnace repair call.

If your furnace won’t turn on, won’t stay on or won’t ignite, try the troubleshooting list below before contacting an HVAC professional.

If you find you need help from an expert and live in Tucson, Ambient Air can help you. We service most types of heating systems.

If you’re ready for a new heating system, we also do furnace replacement in Tucson.

While you’re chatting with us, think over a regular furnace maintenance plan from Ambient Air that might help you avoid repairs in the future. We can tell you how frequently your furnace should be checked by one of our NATE-certified professionals.

Follow our easy guide below to get started on troubleshooting your furnace. Most of these steps don’t require mechanical know-how.

Steps for Furnace Troubleshooting

Check the Thermostat

To begin, make sure your thermostat is signaling your furnace to start.

If you have a digital thermostat:

  • Replace the batteries if the screen is blank. If the digital screen is jumbled, the thermostat may need to be replaced.
  • Make sure the switch is set to “heat” rather than “off” or “cool.”
  • Ensure the program is displaying the right day and time and is set to “run.” If you’re having problems overriding the program, set the temperature by using the up/down arrows and press the “hold” button. This will force the furnace to start if thermostat programming is causing trouble.
  • Increase the temperature setting to 5 degrees warmer than the room temperature.
Digital Thermostat

If your furnace hasn’t kicked on within a couple minutes, make sure it has power by toggling the fan switch from “auto” to “on.” If the fan doesn’t begin to run, your furnace may not have power.

If you have a smart thermostat—like one made by Nest, Ecobee, Lux, Honeywell or Bosch—troubleshooting is very model-specific. Refer to the manufacturer’s website for help. If you still can’t get your Wi-Fi thermostat to work, contact us for assistance.

Lennox Smart Thermostat

Examine Breakers and Switches

Next, you will need to check if your breaker and furnace switch are on.

  • Find your house’s main electrical panel. If you aren’t sure where it is, search for a gray metal box in your basement, garage or closet.
  • Make sure your hands and feet are dry before touching the panel or breakers.
  • Look for the breaker labeled “furnace” or “heat,” and make sure it’s switched “on.” If the breaker has tripped, it will be in the middle or “off” position.
  • Using one hand, firmly switch the breaker to the “on” position. If the breaker immediately trips and pops back to “off,” don’t touch it and get in touch with a professional from Ambient Air at 520-201-3871 right away.

It doesn’t matter how old your furnace is or what brand it is, it has at least one standard wall switch located on or close to it.

  • Make sure the switch is flipped up in the “on” position. If it was turned off, it could take your furnace up to five minutes to ignite. (If you don’t know where to find your furnace, look in your basement, garage or utility closet. It could also be in a crawl space or attic.)

Replace Your Furnace’s Air Filter

When it comes to furnace problems, a dirty, clogged air filter is often to blame.

If your filter is too dirty:

  • Your furnace won’t stay on, or it could overheat from limited airflow.
  • Your energy bills could be higher because your furnace is turning on too often.
  • Your furnace could fail prematurely because a dirty filter causes it to work overtime.
  • Your furnace can be disconnected from power if an excessively dirty filter causes the breaker to trip.

Depending on what model of furnace you use, your air filter can be found inside the blower compartment of your furnace, an attached filter case or wall-mounted return air grille.

Replacing a furnace filter

To replace your filter:

  • Turn off your furnace.
  • Remove the filter and tilt it toward the light. If you can’t see light through it, get a new one.
  • Put in the new filter with the arrow pointing toward the furnace to avoid damage.

Flat filters should be replaced monthly, while pleated filters should last about three months. You can also get a washable filter that will last about 10 years. If you have children or pets, you may have to put in a new filter sooner.

To make the process go more quickly in the future, use a permanent marker on your furnace housing or ductwork to list the airflow direction and filter size.

Examine the Condensate Pan

Commonly known as drain pans, condensate pans hold water your furnace pulls from the air.

If water is dripping out of your furnace or its pan has standing water in it, follow these steps.

  • If your pan has a drain (look for a PVC pipe), check that it isn’t clogged. If it needs to be drained, use a special pan-cleaning tablet you can get at home improvement or hardware stores.
  • If your pan has a pump, inspect the float switch. If the switch is stuck “up” with water in the pan, contact Ambient Air at 520-201-3871, because you will likely need a new pump.

Peek Inside Your Furnace

If malfunctions keep on happening, take a look inside your furnace’s plastic window to check the status of the blower motor. Depending on the model, the light could also be attached on the outside of your furnace.

If you see anything other than a steady, colored light or blinking green light, call Ambient Air at 520-201-3871. Your furnace may be emitting an error code that requires professional help.

Clean the Flame Sensor

If your furnace tries to start but switches off without putting out heat, a dirty flame sensor could be at fault. When this occurs, your furnace will attempt to start three times before a safety feature shuts it down for about an hour.

If you feel comfortable with opening up your furnace, cleaning your flame sensor is something you can do on your own. Or, one of our HVAC specialists at Ambient Air can do it for you.

If you want to clean the sensor yourself, you’ll need:

  • A 1/4” hex screwdriver or wrench
  • Piece of light grit sandpaper, steel wool or emery cloth
  • A dry, clean paper towel

Next:

  • Shut off the furnace’s power by using its wall switch or breaker. If your gas valve is not electric, you will need to shut off the gas as well.
  • Take off the furnace’s front panel and follow the wire to the flame sensor.
  • Unscrew the rod and use your sandpaper, steel wool or emery cloth to lightly rub the metal rod.
  • Wipe off the rod with a paper towel.
  • Remount the sensor.
  • Replace the furnace doors.
  • Turn the furnace’s power back on. It may run through a sequence of checks before resuming regular operation. If your furnace doesn’t start, the sensor may need to be replaced or something else could be wrong. If this happens, get in touch with Ambient Air at 520-201-3871 for assistance.

Relight the Pilot Light

If you have an older furnace, the pilot light could be out. To relight it, find the instructions on a label on your furnace, or follow these steps.

  • Look for the switch on the bottom of your furnace labeled “pilot,” “on” and “off.”
  • Turn the switch to the “off” position.
  • Wait at least five minutes to avoid possibly starting a fire.
  • Turn the knob to “pilot.”
  • Push the “reset” button as you bring the flame of a long lighter to the pilot light opening.
  • Release the “reset” button once the pilot light is lit.

If you have followed the instructions twice and the pilot light still won’t light or stay lit, get in touch with Ambient Air at 520-201-3871.

Check Your Fuel Source

Try turning on another gas appliance. If it doesn’t work, your natural gas service could be turned off, or you could be out of propane.

Ambient Air Can Help with Furnace Problems

Followed our troubleshooting guide but your furnace still won’t work?

Call us today at 520-201-3871 or use our online scheduler. We’ll come out and pinpoint the problem.

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