When your furnace won’t start, doing your own furnace repair in Mission Viejo, California, can feel pretty overwhelming.

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

There are several time-saving, inexpensive fixes you can do on your own to avoid 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 calling an HVAC professional.

If you find you need help from a heating and cooling pro and live in Mission Viejo, 1st Choice Heating & Air Conditioning can help you. We can repair most makes of heating systems and also provide emergency furnace repair.

If it’s time for a new heating system, we also offer furnace installation.

While you’re in touch with us, think over a regular furnace maintenance plan that may help you avoid repairs in the future. We can tell you how regularly your furnace should be inspected by one of our certified professionals.

Use our easy guide below to start troubleshooting your furnace. Most of these steps don’t require mechanical know-how.

Furnace Repair Checklist

1. Check the Thermostat

First, make sure your thermostat is signaling your furnace to start.

Digital Thermostat

Change 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” as opposed to “off” or “cool.”

Ensure the program is showing the right day and time and is set to “run.” If you’re having a hard time overriding the program, set the temperature by using the up/down arrows and press the “hold” button. This will make the furnace to start if thermostat programming is causing an issue.

Increase the temperature setting to 5 degrees warmer than the room temperature.

If your furnace hasn’t kicked 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.

Smart Thermostat

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, call us at 949-204-0859 for heating and cooling service.

2. Examine Breakers and Switches

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

Look for 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.

Find 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 try to reset it and get in touch with a professional from 1st Choice Heating & Air Conditioning at 949-204-0859 right away.

Regardless of 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, anticipate your furnace could 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.)

3. Replace the Air Filter

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

If your filter is too dirty:

  • Your furnace won’t keep heating your home, or it could overheat from reduced airflow.
  • Your energy bills could increase because your furnace is turning on more than it should.
  • Your furnace could fail too soon 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 type of furnace you have, your air filter is located inside the blower compartment of your furnace, an attached filter case or wall-mounted return air grille.

To replace your filter:

  1. Turn off your furnace.
  2. Pull out the filter and hold it up to the light. If you can’t see light through it, replace it.
  3. 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 buy a washable filter that will last about 10 years. If you have children or pets, you may have to put in a new filter more often.

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

4. Inspect the Condensate Pan

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

If water is seeping 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 purchase at home improvement or hardware stores.
  • If your pan uses a pump, take a look at the float switch. If the switch is stuck “up” with liquid in the pan, contact us at 949-204-0859, because you will probably need a new pump.

5. Check for Furnace Error Codes

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

If you see anything other than a steady, colored light or blinking green light, call us at 949-204-0859 for HVAC service. Your furnace may be giving an error code that is calling for professional help.

6. Clean the Flame Sensor

If your furnace tries to start but shuts off without blowing heat, a dirty flame sensor could be responsible. When this happens, your furnace will make an attempt to turn on 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 yourself. Or, one of our heating service professionals 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:

  • Disable 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.
  • Remove 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 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 could proceed through a set of checks before continuing regular operation. If your furnace doesn’t start, the sensor may need to be replaced or something else could be wrong. If this happens, contact us at 949-204-0859 for heating and cooling repair assistance.

7. 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.”
  • 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, contact us at 949-204-0859 for furnace service.

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.

We Can Help with HVAC Repair

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

Call us today at 949-204-0859 or contact us online. We’ll come out and figure out the problem.

Request Service