Why does my furnace not ignite sometimes?

If your furnace won’t ignite, the source of the issue may be a broken flame sensor. The sensor is responsible for turning off the gas burners to avoid gas buildup. Once this component starts to malfunction, it may stop the burners from igniting altogether.

Can hear your furnace click on but it does not fire up?





Most likely, your furnace is making a clicking noise and not providing heat because your furnace’s spark igniter is trying to ignite your pilot light or burners but is failing to do so. In other words, there’s an ignition system malfunction that needs to be fixed. Otherwise, your furnace won’t start.

What are the symptoms of a bad furnace ignitor?

4 Signs of a Faulty Furnace Ignitor

  • The Furnace Stops Running. When a furnace won’t run at all, check for a bad ignitor. …
  • Your Furnace Blows Chilly Air. Unless you’ve set your thermostat to COOL, your furnace should not blow cold air. …
  • Does Your Furnace Short Cycle? …
  • A No Glow Ignitor. …
  • We Can Replace Your Furnace Ignitor.


How do you clean the ignition sensor on a furnace?

Quote from the video:
Quote from Youtube video: So if you have a situation like this what you have 90% of the time is just a dirty flame sensor. So we'll go through the steps on how to clean it. So the right side of the furnace.

Why does my furnace only work sometimes?





Dirty filters are the most common cause of furnace problems. Dust and dirt restrict airflow—and if the filter gets too clogged, the heat exchanger will overheat and shut off too quickly, and your house won’t warm up. If the blower is running but no heat is coming out, replace the filter.

Why does my furnace only kick on sometimes?

If your furnace shuts off too often, you could have a corroded or dirty flame sensor. A flame sensor lets your system know there’s a flame when the gas valve is open. If there isn’t a flame, the sensor will shut off the gas valve to keep the gas from getting into your house.

How do you test a flame sensor?

Quote from the video:
Quote from Youtube video: Then set your meter to measure. Microamps. As soon as the flame is established. You should see a microamp reading on your meter. My manual actually says i'm looking for between one and four microamps.

Can I bypass flame sensor?

Yes. You can bypass the flame sensor. However, if you do so, you can’t manually light your furnace, and you’ve got to have proper bypassing safety measures in place. But it’s advisable not to bypass the flame sensor.

How long do furnaces usually last?



15 to 20 years

A well-maintained furnace can last at least 15 to 20 years, but completing annual maintenance and being diligent with repairs can extend its life even longer.

Can a furnace ignitor be cleaned?

If your furnace has a spark ignitor and it’s working haphazardly, it too could be covered with soot, and a blast of compressed air may be enough to clean it. Compressed air can also clean a blocked pilot tube that is causing the pilot flame to burn weakly or not at all.

How often should a flame sensor be replaced?



Flame sensor lifespan



If you’ve just replaced the sensor or had a new furnace installed, you can expect the flame sensor to last for about five years. The average lifespan of a furnace is 15 to 30 years, so you can anticipate a flame sensor replacement once or twice over the course of your homeownership.

Where is furnace sensor located?

A furnace flame sensor is a very basic part of your furnace. It’s located on the burner assembly and is just a thin metallic rod. It’s usually bent, and it sits just in front of the pilot flame inside the furnace.

Can a flame sensor work intermittently?

The flame sensor is a safety component that detects whether or not there is a flame in the combustion chamber. If this sensor is dirty, the dirt can cause the sensor to operate intermittently. When this happens, your furnace will most likely light, but because the sensor can’t properly detect if a flame is present.

Why do I have to keep resetting my gas furnace?

A furnace reset button is an important feature included with your HVAC system. Designed to quickly shut the unit off, the function is key to safely heating your home. If your furnace reset button keeps tripping, it’s likely that your furnace is overheating. This may indicate a need for furnace repair services.

How many times can I hit the reset button on my furnace?



twice

Don’t hit “reset” more than twice. The process pumps oil into the burner chamber, where it can accumulate if you have no ignition. Then when the furnace finally does start, it can do so explosively. So if the button won’t reset, or quickly pops up again, it’s time to call a professional repair service.

Why does my furnace turn on and off every few minutes?

If your furnace turns off after a few minutes, there is a good chance it is caused by a faulty or dirty flame sensor. This vital component is designed to keep an eye on the gas burner. When it cannot sense that burner, the furnace runs then shuts off and starts again. This could be a relatively easy fix.

How do I know if my furnace is short cycling?

If your furnace turns on and off repeatedly for short bursts of time, not allowing the house to reach its proper temperature, it is short-cycling.

Can a bad thermostat cause a furnace to short cycle?



Thermostat Troubles Can Cause Short Cycling



Your furnace or central air conditioner spends a good amount of energy simply turning on and off, which is why you want yours to run for at least 15 minutes at a time before shutting off.

How do you fix short cycling?

How To Stop and Prevent Short-Cycling

  1. Check your air filter. Believe it or not, a clogged air filter can cause a wide variety of air conditioning issues. …
  2. Check your thermostat placement. …
  3. Check your air conditioner’s refrigerant levels. …
  4. Replace the low-pressure control switch. …
  5. Check the compressor.