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4 Common Reasons Your Furnace Isn’t Working

furnace isn't working

It is never a good feeling when one of your home appliances needs a repair. It is literally not a good feeling when it is freezing in your home because your furnace needs to be repaired. It is not uncommon to experience furnace issues every now and again. The good news is that most common issues have easy fixes. Below we discuss 4 common reasons your furnace isn't working.

Pilot/Ignition Issues

The pilot and ignition are partially responsible for heating the air that runs through your system. If your heater has air coming out but it is running cold, it is most likely due to the pilot and/or ignition. In older unit’s pilot lights are used to light the ignition. These type of pilot lights run constantly and have a strong possibility of going out for various reasons. Though they are inefficient and at times inconvenient due to the frequency they tend to blowout, they are easier to diagnose. Also, relighting a pilot light is a simple and very cost-effective repair. If the pilot is not able to be re-lit it may be that the pilot is faulty and needs to be replaced. If the pilot is not the issue at all, most likely the igniter or ignition module will have to be replaced.

Dirty Burner

Another component of the gas furnace that is responsible for heating is the burner. Gas flows through a line to the burner creating combustion which in turn creates heat. The burner is similar to the AC condenser coil, in the way that it easily becomes dirty from debris. If your furnace isn't working and is blowing cool air it is very possible a dirty burner is the issue. If you have a dirty burner the great news is it normally an easy and non-expensive repair.


It may seem too good to be true but many issues you may experience may be simply caused by thermostat setting or thermostat condition. The thermostat is always a great place to start if you suspect you are having furnace issues because most times it is an easy fix you can take care of yourself. The first thing to check is to make sure that your thermostat is set on heat and not fan or cool. The second is to make sure that scheduling is not set incorrectly. If you have a smart thermostat you want to make sure that auto scheduling is disabled. Most learning thermostats will program themselves based off your patterns so you may have an auto schedule in place and not be aware. Many people forget to change their settings when the weather cools down. The third would be to check your thermostat batteries. If it is time to change the batteries, there is a good chance that your thermostat may be malfunctioning.

High-Limit Switch

A common and often frustrating issue with furnaces is short cycling. This is often caused by problems with the high-limit switch. The high-limit switch is an important component that reads the temperature in the plenum and instructs the blowers when to blow to circulate the air. If your furnace is short cycling it could be that the limit switch is turning it off. There are a couple of reasons this occurs. The system can begin to overheat if there is poor airflow which will cause the limit switch to turn off before it reaches the desired temperature in the home. Low airflow is predominantly caused by clogged filters. After sometime, high limit switches can begin to malfunction due to age and turn the blowers on and off. At that time, they would need to be replaced.

Some of these issues are simple fixes, while the others are more costly and complex. The easiest way to minimize any of these issues occurring is to have your furnace maintained regularly. Give LA Construction, Heating and Air a call today and schedule your annual furnace maintenance! (818)341-3406 or contact us online we are here to help!

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