5 Reasons Why Your Furnace Turns Off After a Few Minutes

Your furnace is a vital part of your HVAC system. It can however start to turn off and on every few minutes, why is it that?

If your furnace is turning off and on continuously, you have a problem with restricted airflow, dirty flame sensor, faulty pressure switch, control board failure or your furnace is short cycling.

Below you’ll find out how to fix these issues you’re having with your heating system.

Let’s get started.

5 Reasons Why Your Furnace Turns Off and On Continuously

1. Airflow is restricted

Your furnace requires adequate airflow to work properly. I

If it doesn’t have enough airflow, then the heat exchanger will overheat.

Overheating is more likely to occur if your furnace is a closed storage space without proper ventilation.

Your heat exchanger is designed to turn off once it reaches a certain temperature.

Check if the air inlet from the outside of your home is blocked with any debris. Also check if your air filters are clean as well as positioned in the proper direction.

Airflow can become restricted if your air filter is installed backwards causing your furnace to turn off and on every few minutes.

If there is no block in the outdoor air inlet and your filters are clean and installed properly, your furnace is likely getting enough airflow.

If the room is fairly small and houses your furnace, you can try to open the door or a window to see if that helps your furnace stay on.

Without enough oxygen, the fire will die out.

2. Faulty Pressure Switch

The pressure switch is what asses the pressure of your furnace when it turns on.

If your furnace is working properly and is creating negative pressure, the pressure switch closes.

If the pressure switch senses that your furnace isn’t venting properly, then it will prevent your furnace from turning on.

If your pressure switch is failing or is faulty, it will not let your furnace stay on.

It’s a vital safety precaution that prevents exhaust fumes from getting into your home. If you have a multimeter, you can check your pressure switch to see if it’s working properly.

3. Control Board is Failing

Not all furnaces use a control board, but if you have an electric furnace or your gas furnace uses a control board, then it’s possible that your control board is faulty or dying.

Your furnace will not be given adequate electricity which will not allow it to stay on.

If your electric or gas furnace shuts off after a few minutes of running, it’s possible that you’ll need to replace the control board.

4. Short Cycling

A short cycling furnace is when your furnace is turning off and on more than 8 times per hour. If this is happening to you, it may be normal depending on how cold it is outside.

If it’s fairly cold, then your furnace has to work harder to heat your home.

Other problems that may cause short cycling are that your furnace is the wrong size, your furnace is dying, your furnace is overheating, or the thermostat is broken.

5. Dirty or Faulty Flame Sensor

Your flame sensor will shut the gas valve if it does not detect any fire. This is to prevent any explosions that may occur within the combustion chamber from built up gas that may suddenly explode.

If you have a dirty flame sensor, it will malfunction and not be able to sense any fire. It can also be the reason why your furnace doesn’t stay on.

The best way to clean your flame sensor is by removing it and wiping off any built up grime or soot with light grit sandpaper.

Do not overly grind down your flame sensor, only enough to remove any particles that are caked on.

A dirty flame sensor can also cause your pilot light to not stay lit.

When to Call HVAC Experts?

Having issues with your heating system can become an emergency during the coldest months of the year.

If you have tried to troubleshoot your furnace but nothing is working, you can call on our HVAC technicians to come to give you a hand.

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