Furnace Repair in St. Louis, MO

HVAC man working on a furnace

When your heater won’t kick on, doing your own furnace repair in St. Louis, MO, can appear overwhelming.

There are several time-saving, low-cost solutions you can do yourself to avoid a heater service call.

If your heater won’t turn on, won’t run consistently or won’t fire, take a look at the troubleshooting guide below prior to contacting an HVAC expert.

If you realize you need support from a heating and cooling expert and live in St. Louis, Morgner Inc. Air Conditioning & Heating is able to help you. We have the ability to repair most types of HVAC systems.

CALL NOW 314-262-4541

If you’re ready for a new heater, we also provide furnace installation.

While you’re chatting with us, think over an annual furnace maintenance plan from Morgner Inc. Air Conditioning & Heating that may help you avoid problems down the line. We can tell you how regularly your heater ought to be inspected by one of our NATE-Certified professionals.

Go through our easy checklist as follows to get to work on troubleshooting your heating system. The majority of these steps don’t require mechanical skills to complete your furnace repair.

Furnace Repair Checklist

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1. Check the Thermostat

First, make certain that your thermostat is telling your heat to turn on.

Digital Thermostat

  • Replace the batteries if the screen is not displaying anything. If the digital monitor is jumbled, the thermostat could need to be swapped out.
  • Ensure the button is switched to “heat” instead of “off” or “cool.”
  • Make sure the program is showing the correct day and time and is scheduled to “run.” If you’re having a hard time turning off the schedule, set the temperature by utilizing the up/down arrows and holding the “hold” button. This will cause the furnace to start if thermostat is causing an issue.
  • Turn the temperature setting to 5 degrees above what the room temperature currently is.

If your heating hasn’t turned on within a couple minutes, make certain that it has power by changing the fan switch from “auto” to “on.” If the fan doesn’t start, your heater may not have power.

Smart Thermostat

If you have a smart thermostat—such as one designed by Nest, Ecobee, Lux, Honeywell or Bosch—troubleshooting will be determined by the model you have. Refer to the manufacturer’s website for help. If you aren’t able to get your Wi-Fi thermostat to work, reach us at 314-262-4541 for heating and cooling service.

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2. Inspect Breakers and Switches

Next, confirm your breaker and furnace switch are on.

  • Locate your main electrical panel. If you aren’t sure where it is, look for a gray metal box in your basement, garage or closet.
  • Make certain that your hands and feet aren’t wet prior to opening the panel or breakers.
  • Find the breaker labeled “furnace” or “heat,” and ensure it’s reading “on.” If the breaker has tripped, it will be in the middle or “off” area.
  • Moving one hand, firmly switch the breaker to the “on” position. If the breaker instantly trips and pops back to “off,” don't try to reset it and get in touch with a professional from Morgner Inc. Air Conditioning & Heating at 314-262-4541 right away.

Regardless of your furnace’s age or brand, it has no less than one regular wall switch installed on or near it.

  • Ensure the control is moved up in the “on” position. If it was switched off, anticipate your furnace could take up to five minutes to ignite. (If you don’t know where to locate your furnace, check your basement, garage or utility closet. It may also be in a crawl space or attic.)
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3. Buy a New Air Filter

When we consider furnace issues, a dirty, clogged air filter is regularly to blame.

If your filter is too dusty:

  • Your furnace won’t keep heating your home, or it may overheat from reduced airflow.
  • Your gas expenses may increase because your heat is turning on more than it should.
  • Your furnace may fail too soon due to the fact a dusty filter triggers it to work harder.
  • Your heating may be disconnected from power if an extremely dirty filter causes the breaker to trip.

Based on what model of heating system you have, your air filter can be found within the blower compartment of your furnace, an attached filter case or wall-mounted return air grille.

To swap out your filter:

  • Turn off your heating system.
  • Take out the filter and angle it toward the light. If you can’t see light through it, replace it.
  • Put in the new filter with the arrow facing toward the heater to keep damage from happening.

Flat filters should be replaced every month, while pleated filters should last about three months. If you have children or pets, you could have to replace your filter more often.

To make changing your filter easier down the road, draw with a permanent marker on your heater outside or ductwork to indicate the airflow direction and filter size.

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4. Inspect the Condensate Pan

Commonly known as drain pans, condensate pans catch liquid your heating system pulls from the air.

If moisture is seeping from within your furnace or its pan is overflowing, try these recommendations.

  • If your pan includes a drain (look for a PVC pipe), check that it isn’t full. If it needs to be drained, use a special pan-cleaning tablet you can buy at home improvement or hardware shops.
  • If your pan contains a pump, take a look at the float switch. If the button can’t be moved from the “up” position with liquid in the pan, reach us at 314-262-4541, because you will likely have to buy a new pump.
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5. Look for Heater Error Codes

If faults persist, peek at your heater’s plastic window to verify the blower motor’s status. Subject to the type, the light may also be attached on the exterior of your furnace.

If you notice anything except a steady, colored light or twinkling green light, contact us at 314-262-4541 for HVAC service. Your heater could be emitting an error code that needs specialized assistance.

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6. Scrub the Flame Sensor

If your heater attempts to operate but switches off without blowing heat, a grimy flame sensor can be to blame. When this takes place, your furnace will try to turn on three times before a safety feature shuts it down for about an hour.

If you feel okay with opening up your heater, brushing off your flame sensor is a job you can do personally. Or, one of our heating service specialists can finish it for you.

If you are fine with cleaning the sensor yourself, you need:

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


  • Disable the heating system’s power by using its wall switch or breaker. If your furnace’s gas valve isn’t electric, you have to turn off the gas in addition.
  • Take off the furnace’s front panel and trace the wire to the flame sensor.
  • Take off the rod and use your sandpaper, steel wool or emery cloth to lightly scrub the metal rod.
  • Wipe off the rod with a paper towel.
  • Screw the sensor back in.
  • Replace the furnace doors.
  • Restore power to the furnace. It could go through a sequence of inspections before proceeding with usual operation. If your heater doesn’t ignite, the sensor may require replacement or something else might be causing a problem. If this takes place, call us at 314-262-4541 for heating and cooling repair support.
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7. Reignite the Pilot Light

If you are using an outdated furnace, the pilot light could be out. To reignite it, look for the directions on a sheet on your furnace, or follow these guidelines.

  • Locate the lever on the bottom of your heating system marked “pilot,” “on” and “off.”
  • Move the switch to the “off” position.
  • Take a break for at least five minutes to limit the possibility for starting a fire.
  • Push the knob to “pilot.”
  • Press the “reset” switch as you bring the flame of a long lighter to the pilot light opening.
  • Release the “reset” button once the pilot light is burning.
  • If you have used the list twice and the pilot light still won’t ignite or stay ignited, call us at 314-262-4541 for furnace service.

condensate pan icon

Double-Check Your Gas Delivery System

Try switching on a second gas appliance. If it doesn’t work, your natural gas source could be shut off, or you may have run out of propane.

We Can Provide Furnace Servicing

Went through our troubleshooting checklist but your heater still refuses to heat?

Contact us today at 314-262-4541 or contact us online. We’ll come out and figure out the issue.


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