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Why is My Home Central Heater Not Working?

home central heater blows cold air

When you find your home central heater not working, there could be several causes. Two of the most common reasons your home central heating isn’t working are a dirty flame sensor and a dirty air filter. Clean the flame sensor with a steel wool pad and replace the air filter every 1-2 months. This will help prevent future problems.

How to Troubleshoot Your
Home Central Heater Not Working

A dirty flame sensor or furnace filter are just two reasons you may have a home central heater not working issue. Use the troubleshooting guide below if you’re wondering, “Why is my heat not coming on?” You’ll be toasty again in no time.

#1 Dirty Flame Sensor

This is typically the most common cause when you find your home central heater not working. If your furnace turns on then immediately shuts off, this could be a sign that your heater flame sensor is dirty.

The flame sensor is a stainless steel L-shaped rod located behind the burners, opposite the igniter. Follow these steps to clean your flame sensor:

  • Turn off your furnace power switch and locate the flame sensor, unscrewing the protective metal plate in front of the burners if necessary.
  • Rub the uncovered, stainless steel portion of the sensor vigorously with a steel wool pad to remove any build-up.
  • Replace the sensor and turn your furnace power switch back on.
how to clean dirty flame sensor
Photo Credit: Word of Advice TV

#2 Dirty Air Filter

A home central heater uses an air filter to screen out dust, allergens, and dirt particles when blowing warm air throughout the home. Again, if your furnace turns on then off immediately, you may need to replace your air filter. Another sign of a dirty air filter is if your heater blows cold air only.

Replacing an air filter can be fairly straightforward. Most are located just before the return duct in front of your furnace. Follow these instructions for how to change a dirty air filter:

  • Remove the dirty filter from the front of the return duct.
  • Replace it with a new one, making sure that you follow the arrow on the side of the filter to install it correctly.

Don’t Forget: Typically one side of the filter will have a wire net in it. Install it with this side facing the furnace and its blower fan.

If your filter is excessively dirty, the furnace fan may have pulled the filter in towards the motor. In this case, use care when removing a bent or twisted filter to avoid damaging any furnace components.

We recommend using a medium grade filter where the fiberglass accordion pleats are neither too tight nor too wide for optimal performance. Air filters should generally be changed every 1-2 months to avoid reoccurring problems.

why is my home central heater not working
Photo Credit: Filtrete

#3 Bad Inducer Motor

A home central heater not working or turning on oftentimes indicates a failed inducer motor. The inducer motor cleans the area of the furnace where the air is heated, ridding it of any heating byproducts or remnants. It’s a wide, cylindrical component near the top of the furnace.

You’ll know the inducer motor is malfunctioning if you remove the furnace door and it’s extremely hot to the touch.

Sometimes an inducer motor will fail if there’s something caught in the motor’s fan. However, if you’re able to see the fan and move it somewhat freely with a screwdriver, it’s likely that there’s no blockage. In this case, the inducer motor is faulty and will need to be replaced by a home heating professional.

Photo Credit: Word of Advice TV

#4 Bad Blower Motor

The blower motor of your home heating system actually blows the warm air that the furnace creates to the rest of your home. The blower motor is typically located at the bottom of the furnace facing your air filter. On the opposite side of the furnace is the blower wheel.

Signs that your blower motor is causing your furnace problem include:

  • The blower wheel turns on slowly before immediately turning off.
  • The blower wheel doesn’t turn with ease.
  • The blower motor is hot to the touch, at which point you may smell a burning smell coming from the furnace.

While chronically clogged filters can cause blower problems, other times components of the blower system can be faulty. Typically a professional will replace the motor, blower wheel and the capacitor.

home central heater not working but ac is
Photo Credit: Word of Advice TV

#5 Furnace Blowing Cold Air

Is your heater blowing cold air? There are actually multiple causes that can be relatively simple fixes for this issue. Below are some common reasons for central heating not working but AC is:

Thermostat is set to ‘cool’ instead of ‘heat’.
Reset the thermostat accordingly.

Thermostat batteries are dead.
Even batteries that are not completely dead can cause thermostat malfunctions.

Thermostat needs to be recalibrated.
Confirm that your thermostat is operating correctly by verifying the room temperature with another temperature reading device.

Heating system not receiving power.
Check your circuit breakers to make sure a switch isn’t flipped. If it is, flip the switch back to the correct position.

Heater needs to be reset.
If your heating system has a reset button, push it to reset the system and clear it of any minor computer glitches.

Air filter needs to be replaced.
Restricted airflow could overheat your furnace, causing it to shut down as a protective measure.

Air vents are blocked.
Obstructions can affect the temperature of a room by limiting airflow.

If these simple checks still have your furnace blowing cool air, furnace components such as the igniter or high limit switch may need repair. The ductwork for your system may have holes, leaks or blockages as well. We suggest consulting a professional to help make this assessment.

We hope this guide answered the question, “Why is my home central heater not working?” for you. Oftentimes, simple fixes and regular maintenance can solve many home heating problems.

When the cause for your central heat not working proves to be more complicated, Dependable Heating & Air is happy to assist with a central heater repair. Call us to help you stay snug on a cold winter’s night!

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