Why Did My Furnace Turn Itself Off

Why Did My Furnace Turn Itself Off?

Understanding your furnace can save you a lot of money when something isn’t quite right. This past winter wasn’t the coldest we’ve ever experienced, but according to our furnace it took a beating non the less. Over the course of the winter, and I used this term loosely as it is April and we have fresh snow on the ground right now and it is ‘supposedly’ spring!

We had to call in a professional three times to look at our furnace and it cost us personally over $300 in all! Which is utterly ridiculous when we learned what we had done wrong! Learn from my mistakes as always and pay attention to your furnace and spend that hard earned cash on something other than a service person, because you can totally do this!

Why is My Furnace Not Working?

One cold winter morning while working from home I noticed my house was a little chilly, so I went over to the thermostat and it was 64 degrees. I have a toddler and so I thought he might have been messing with the buttons, since it isn’t child proof or anything. I turn it back up to 70 degrees. I waited, and the furnace doesn’t kick on, there is no air hot or cold coming from the vents.

The thermostat drops another degree. It is getting colder! I grab a hoodie and put it on. I go downstairs to ‘assess’ the situation, as if I even know what I am looking for. I look at the furnace. It is there, and it is quiet. I have no idea why. I have no idea how to fix a furnace, what am I going to do? I call my husband while he is at work to ask him how does our furnace work to see if he can help me figure this out.

We discuss how to reset the furnace, but I am pretty clueless on what I am even looking at and we decide I usually can cause more trouble than I can fix when it comes to ‘handy work’. We decide that with the extreme cold temperatures I should just call it in and get a professional to come out and take a look.

Furnace Filters

We were lucky, and someone is able to come out and check out our furnace quickly, so hopefully we don’t have to sleep in a cold house or go to a hotel for the night. In less than a minute the service person knows exactly what happened! How is that possible?! He calls me to come downstairs to take a look. I come downstairs and he pulls the furnace filter out and it is just FILTHY!

I have never seen one so dirty in all of my days except if you google dirty filters you might come across one as dirty or almost as dirty as the filter we had. The furnace filter wasn’t allowing the furnace air to flow through it instead of overheating and breaking, the furnace is made to automatically shut itself off to avoid damage.

This is pretty smart, except I had no idea that I needed to replace my filter. My husband had always been the one staying on top of changing the HVAC filter. However, over the last year he had become overwhelmed with assisting his elderly parents with doctor visits, medical issues, nursing home, finances etc. Changing the filter had dropped off his radar, and I didn’t pick it up.

I got a quick lesson on furnace filters and he advised that we should use the ‘cheap’ filters. The ones that catch the most allergens actually make your furnace work extra hard to allow air flow through your furnace because they are thicker.  Who knew thicker wasn’t actually better?!

HVAC Furnace Filters 101

cheap and flimsy furnace filterThis filter is cheap and flimsy, this is actually what you want to buy, unless for some strange reason you want to spend an obscene amount of money on a filter and it only provides slightly better air quality and you need to change them frequently as well as it makes your furnace work harder than it needs to.

thick, sturdy and expensive furnace filter

This filter is thick, sturdy and expensive, do not buy this unless you are told you have to for health reasons, but be prepared to replace them frequently to allow enough air flow to not shut off your furnace.


What Does Your Furnace Need to Run?


Power for furnace cleaningOnce you learn what causes your furnace to shut off, it can help you problem solve why it shut off on your own, without paying a professional to tell you. Do you think your furnace is getting power? If you think it is shut off, go to the fuse box in your house and see if the switch is on or off. You should go ahead and flip it all the way off and all the way on, as it could have only partially tripped and you may not notice that it is only partially turned on. It won’t hurt your furnace to flip the switch, but it will hurt to pay a bill of $100 or more for the service person to show you that your furnace switch was off, when you didn’t check!

If there is no power going to your furnace your thermostat might show blank – instead of a temperature. Also, many brands of furnaces have a light and if the light is not there, you might not have power. If the light is there and it is blinking, your furnace might be telling you what is wrong with it! It’s like a cool Morse code that your furnace speaks. So, if you have a manual or access to Google you might be able to understand what is wrong with your furnace!


Funny gas furnace resetIf your furnace is not receiving gas to run, this could be if your forgot to pay your gas bill! Call your gas company to make sure it wasn’t accidentally shut off! As new homeowners might have had an oversight of putting the gas bill in their name after buying the home and moving in. From experience I did that with the water company, with my first home purchase! If there is another issue, having the gas company come out is a good idea.

If you smell gas call them right away and take you and your family and pets out of the home immediately, call the fire department to come in and inspect it. A gas leak is NO JOKE and needs to be taken seriously. As long as you paid your bill or set up the account with your gas company, and there is no leak your furnace should be getting gas into it.

Air Flow

Air flow is allowed through your HVAC furnace filter. If your filter is dirty, like mine was the first time I called for a service on my furnace this year it is clear as to why the furnace shut itself off. However, I learned, again the hard way, that your filter can appear to look clean and still be full. If your furnace is not getting enough airflow, it will shut off. You remove the dirty filter and replace it, turn the trip switch off and on and it should restart your furnace.

My Furnace Isn’t Working…Again

So fast forward to more winter and my family has been enduring the winter colds and flu bugs and we are just about over the ailments and I am of course working from home and notice our house is again a little chilly. I follow all the steps I did the last time. I turn up the thermostat to see if my child turned it down. After an hour or so the temperature hasn’t risen. I go downstairs to check and see if the filter is dirty. It doesn’t appear to be filthy, especially not like last time! I check the fuse box to see if it was switched off.

None these things appear to be the issue. So, I again call my husband and who asks me to check all the things I just did. I tell him I did it all and I see no reason for our furnace to not be working. I call for a furnace repair person to come take a look.

Again, within minutes, the HVAC repairman is able to see exactly what went wrong?! How can this be!? UGH… I guess I am glad it should be an easy fix, but I hate paying over $100 for someone to tell me something I feel like I should be able to fix myself. He told me the filter was full. I look at him with the deer in headlights look… It is not dirty!

I just looked at it. He then asked if we have been running humidifiers in our home. I say yes, my family has been sick. He says the furnace filter is full of moisture, which made the filter not able to pass air flow through it, causing the furnace to trip itself off… again.

Confused, I take him upstairs to ask him what humidity I should have set the humidifier to. Apparently the one on my wall. Next to my thermostat is merely a decoration. It isn’t even connected to anything!

So, I learned I do not have a humidifier in my home, which I have been adjusting for over six years now. Feeling embarrassed and defeated we go back to the basement to look at the furnace. He explains that because we are running separate humidifiers in our bedrooms that it has put enough moisture into our furnace to clog up our air filter. If we are going to continue to use the humidifiers, we need to replace the filters every two weeks. It is a good thing we started buying the inexpensive ones! We remove the moisture clogged air filter and replace it with a new one and trip the furnace off and on and it restarts. Another $100 Furnace 101 lesson for me.

Oh My God My Furnace Is Not Working Again!

Bear with me! As you need to know that even after following all these instructions from the furnace repair specialist, I still experienced yet another time where my furnace decided to shut itself off. Again, I am working from home. Notice that it is a little chilly, follow all the same steps yet again. I cannot get the furnace to work!…

This time I actually try to reset the furnace myself. I look at the filter, it does not look dirty. I flip the trip switch in the fuse box and I wait. Still nothing turns on, so feeling completely defeated by my furnace I make the call, again.

After learning about the humidifiers, I moved them away from the air intake vents to avoid having them suck so much moisture into them. I believe this bought me more time before the filter would get clogged up again with moisture.

bowed furnace filterThe furnace repair specialist arrives and states that my filter is clogged, annoyed I explain my entire saga you have read so far. He says to an untrained eye it might not look like it is a dirty filter, but he turned the filter and showed it to me on its side and said here you can see it is bowed. When your  that means the furnace isn’t able to get the air flow through the filter, causing it to bow.

You can see a slight bend in the filter below showing that it was bowing. Which is yet again why my furnace shut itself off. This time the service man felt bad and gave our furnace a good cleaning while he was there, so at least I don’t have to pay for that in the spring, whenever spring decides to get here!

How to Reset Your Furnace

So, after everything I have endured / learned over this last winter, we know that furnace air flow is vital! You need to have appropriate furnace air filters for your home. We learned that the best air filter is likely not the most expensive one, but the least expensive one, despite what common sense would tell us!

We know that if you are sick running a humidifier in your home may cause your furnace filter to be clogged with moisture and that clogged air filter may appear to be clean, but even if you think it is clean spent the $3 to replace it every two weeks while you are running humidifiers in your home for your family’s illnesses!

So, when your furnace shuts itself off, check for power, gas, and air flow. If you have a dirty filter, replace it, trip the switch in the fuse box and it should reset your furnace. Learning how to take care of your furnace and not have it over work itself will help save your furnace on replacing furnace parts, repairing your furnace and hopefully avoid replacing your furnace and having to cover a new furnace cost, which is usually several thousand dollars!

1 thought on “Why Did My Furnace Turn Itself Off?”

  1. Cynthia Johnson

    I have service with American Home Shield since September 2009. I am happy with AHS. This is a furnace call. Starting in January 2019 a HVAC technician has been to our home three times February and March. Heat unit stop working in January. HVAC technician added Freon. Recall AHS in February unit was not heating properly. Technician discovered thermostat was not working. He installed new thermostat. March another recall furnace started making noise and burning smell. HVAC technician returned on March 8th replaced blower motor, capacitor and wheel. March 17th the furnace started making that loud noise again thermostat started sparking house filling up with smoke dial 911 for the Fire Department. HVAC technician returned on March 18th. After several to AHS to find out happen I was told that the HVAC contractor said it was a Power Surge. The only thing burned up was the furnace and thermostat everything else is working in the house. AHS denied the claim for repairs. We know the contractor company was at fault but AHS still denied the claim. We feel the contractor company was covering themselves by saying it was a Power Surge that they caused…AHS warranty customers just wanted you to be aware of what happen to us….

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