furnace repair

Phoenix 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 several fast, inexpensive fixes you can do by yourself to prevent 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 getting in touch with an HVAC professional.

If you find you need help from an expert and live in Phoenix, Dial One Mears Air Conditioning & Heating Inc can assist you. We service most makes of heating systems.

If it’s time for a new heating system, we also provide furnace replacement in Phoenix.

While you’re in touch with us, consider an annual furnace maintenance plan from Dial One Mears Air Conditioning & Heating Inc that may help you avoid breakdowns in the future. We can tell you how often your furnace should be checked by one of our NATE-certified specialists.

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 instructing your furnace to ignite.

If you have a digital thermostat:

  • Swap out 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” instead of “off” or “cool.”
  • Ensure the program is set to 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 cause the furnace to turn on 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 turned on within several 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 might not have power.

If you have a smart thermostat—like one made by Nest, Ecobee, Lux, Honeywell or Bosch—troubleshooting is very model-specific. Take a look at 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.

  • Locate your house’s main electrical panel. If you have no idea where it is, look 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 contact a professional from Dial One Mears Air Conditioning & Heating Inc at 602-832-7808 right away.

No matter your furnace’s age or brand, it has at least one standard wall switch located on or near it.

  • Make sure the switch is flipped up in the “on” position. If it was turned off, expect your furnace to take up to five minutes to ignite. (If you don’t know where to find your furnace, take a look at 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 filthy, clogged air filter is frequently to blame.

If your filter is too dirty:

  • Your furnace won’t stay on, or it could overheat from restricted airflow.
  • Your energy bills could increase because your furnace is turning on too often.
  • Your furnace could break down sooner than it should because a dirty filter causes it to work harder.
  • Your furnace can lose power if an extremely dirty filter causes the breaker to trip.

Depending on what type of furnace you own, your air filter is located 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 hold it up to the light. If you can’t see light through it, replace it.
  • Insert the new filter with the arrow pointing toward the furnace to avoid damage.

Flat filters should be replaced every month, while pleated filters should last about three months. You can also buy a washable filter that will last about 10 years. If you have children or pets, you may have to replace your filter more often.

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

Examine the Condensate Pan

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

If water is leaking 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’s clear. If it needs to be drained, use a special pan-cleaning tablet you can buy 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 Dial One Mears Air Conditioning & Heating Inc at 602-832-7808, because you will probably need a new pump.

Peek Inside Your Furnace

If malfunctions persist, look inside your furnace’s plastic window to verify 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 Dial One Mears Air Conditioning & Heating Inc at 602-832-7808. Your furnace may be communicating an error code that requires professional service.

Clean the Flame Sensor

If your furnace tries to start but switches off without putting out heat, a dirty flame sensor could be to blame. When this occurs, your furnace will try to start three times before a safety feature powers 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 professionals at Dial One Mears Air Conditioning & Heating Inc 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.
  • Lift off the furnace’s front panel and track the wire to the flame sensor.
  • Unscrew the rod and use your sandpaper, steel wool or emery cloth to carefully 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 could run through a set of checks before continuing usual operation. If your furnace doesn’t turn on, the sensor may need to be replaced or something else might be wrong. If this happens, get in touch with Dial One Mears Air Conditioning & Heating Inc at 602-832-7808 for assistance.

Relight the Pilot Light

If you are using 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.

  • Locate 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 creating a fire.
  • Turn the knob to “pilot.”
  • Press 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, call Dial One Mears Air Conditioning & Heating Inc at 602-832-7808.

Check Your Fuel Source

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

Dial One Mears Air Conditioning & Heating Inc Can Help with Furnace Problems

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

Call us today at 602-832-7808 or use our online scheduler. We’ll come out and pinpoint the problem.

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