It is such a bad feeling when you struggle to get home on a cold winter night and realize that your furnace is out. You can check the pilot light and even relight it, but if your furnace still won’t turn on, there may be a bigger problem.
Before you panic, there are several reasons why your furnace won’t turn on. We’ll explain the most common causes and what you can do about them. But you should realize that only a trained professional like the HVAC technicians at Robert B. Payne should attempt to fix your furnace.
How Does Your Furnace Work?
If you want to know why your furnace isn’t working, it’s helpful to understand how it works.
Your furnace has a pilot light that ignites the burners. The heat from the burning gas warms up the air, which is then distributed through your home via ductwork. But before then, the process starts when your indoor temperature goes below the thermostat setting. Your thermostat then sends a signal to the control board for heating to commence. Thereafter, flue gases are vented out of your house while fresh air is brought in to support combustion.
Top Reasons Why Your Furnace Won’t Turn On
Now that you understand how your furnace works, let’s look at some reasons why it may not turn on.
Your Furnace Won’t Turn on Because The Switch is Off
Our HVAC experts have seen it all, and one common problem is that the switch powering the furnace is turned off. The switch could be on the wall near your furnace or even on the furnace itself. If the switch is in the “off” position, flip it up and check to see if your furnace is getting power. If yes, your work is done. If not, read on to the next section.
You Have a Tripped Circuit Breaker
Another common reason your furnace won’t turn on is a tripped circuit breaker. If your furnace still won’t turn on after the first step above, the next thing you should check is your home’s circuit breaker. If the breaker has tripped, simply flip it back on and try to turn on your furnace again.
Your Gas Valve Isn’t on
If the gas valve shutoff on your furnace is in the “off” position (when the handle is perpendicular to the gas line), your furnace won’t turn on. The gas valve is usually located near the bottom of your furnace. Once you find it, simply turn it to the “on” position (parallel to the gas line) and see if your furnace starts working again.
Your thermostat is one of the most important parts of your furnace. If it’s not working properly, your furnace won’t turn on. There are several things that could be wrong with your thermostat. The batteries could be dead. That is why you need to always have replacement batteries on hand. If the batteries are not the problem, the issue could be with the thermostat itself. In this case, you may need to replace your thermostat.
Loose or Damaged Thermostat Wiring
For your thermostat to send the signal to turn on your furnace, the wiring must be intact. If there are any loose wires or damage to the wiring, your furnace won’t turn on. This is a job for a professional like the ones at Robert B. Payne. But you can check to see if the wires are flawless.
Wrong Thermostat Settings
Your thermostat should be set to heat for the furnace to turn on. If it’s not, adjust it and see if your furnace starts working again. You should also check to see if it’s set to “fan only”. If it is, change the setting to “auto”.
You should ensure that your thermostat is not set at a level that is too low for your home. If you don’t have a programmable thermostat, you should get one. It will give you more control over your furnace, and you can set it to a lower temperature when you are away from home to save on energy costs.
Your Furnace Won’t Turn on Because of a Bad Capacitor
Your furnace has a capacitor that helps to start and run the furnace motor. If the capacitor is damaged or faulty, your furnace won’t turn on. You’ll need a technician to test the capacitor and replace it if necessary.
Your Furnace Won’t Turn on Due to Blower Motor Issues
If your furnace’s blower motor is dirty or not working, your furnace won’t turn on. The blower motor is responsible for moving air through your furnace. If it’s not working, the furnace won’t turn on. You’ll need a technician to clean or replace the blower motor. If the blower motor is dirty, it will find it hard to move air over the heat exchanger, and this will make your furnace work harder and use more energy.
The first thing you should do is check to see if the switch that powers the blower motor is turned on. If it is, the problem could be with the motor itself. You’ll need a professional to take a look at it and determine if it needs to be cleaned or replaced.
Your Furnace Won’t Turn On Because of a Dirty Air Filter
Proper airflow is essential for your furnace to work correctly. If the air filter is clogged, it will restrict airflow and cause your furnace to overheat. A dirty air filter can also cause your furnace to cycle on and off too frequently.
You should check your air filter every month and replace it if it’s dirty. A new air filter will allow proper airflow and help your furnace run more efficiently. If you do not have pets in your home, we recommend replacing your air filter every 3 months. If you can’t do it on your own, please contact our office and we will gladly help you.
Your Furnace Won’t Turn On Because the Flame Sensor is Triggered
The flame sensor is a small rod that is located near the burner in your furnace. Its purpose is to detect whether or not there is a flame present so that it lets the gas valve open. If the sensor is dirty, it can trigger the safety switch and cause your furnace to shut off. With time, your flame sensor may get covered in carbon buildup which will cause it to become less sensitive.
Set Off Door Switch
The furnace door switch is located on the access panel of your furnace. Its purpose is to shut off the furnace when the door is removed. If this switch is loose or damaged, it can cause your furnace to shut off. Check for loose cabinets, boxes, or other objects that may be blocking the switch and preventing it from working properly.
Safety Float Switch Shuts Furnace Down
There’s a condensation drain pan located under your furnace. The purpose of the pan is to collect any condensation that forms on the heat exchanger. If this pan fills up, it will trigger a safety switch which will cause your furnace to shut off. This prevents water from spilling all over your home and causing damage.
You should check the pan regularly and empty it if necessary. If you have a clogged condensate line or drain, it will cause the pan to fill up more quickly. You’ll need a professional to clean or replace the line.
High Limit Switch is Set Off
The high limit switch in your furnace communicates with the thermostat to tell the furnace when to turn on and off. This helps to prevent the furnace from overheating. If the high-limit switch is dirty or faulty, it can cause your furnace to shut off. You’ll need a professional to test the switch and clean or replace it if necessary.
Triggered Pressure Switch
A pressure switch shuts down your HVAC system if there is a blockage in the ventilation system. It prevents flue gases from entering your home. If the pressure switch is triggered, it will cause your furnace to shut off. If the pressure switch is dirty or damaged, it may wrongly trigger and cause your furnace to shut off. You’ll need a professional to inspect the ventilation system and clear any blockages to keep your home safe.
Alerted Flame Roll Out Switch
When your burner is ignited, the flame should be contained within the furnace. A cracked heat exchanger, a blocked flue pipe, or some other issues can cause the flame to roll out. If the flame rolls out of the furnace, it can cause a fire. The flame rollout switch is designed to detect when this happens and shut off the furnace. If your furnace keeps shutting off, it could be because the flame roll out switch is being triggered.
There are many reasons why your furnace won’t turn on. These are some of the most common ones. Some of these problems can be fixed easily, while others will require the help of a professional. If you’ve checked all of these things and your furnace still won’t turn on, contact us at once.
How Best to Avoid No Heat This Winter
Prevention is always the best medicine. You can avoid no heat this winter by taking some preventative measures now. The best thing you can do is to schedule a maintenance visit from a heating contractor. This is the best way to ensure that your furnace is in good working order and that any potential problems are caught early.
During a maintenance visit, the contractor will clean and inspect your furnace. They’ll also test all of the safety features to make sure they’re working properly. This is something you should do every year before the winter season begins.
Get In Touch For More Information
We hope this article was helpful and that you were able to find the reason why your furnace won’t turn on. If you have any further questions, please don’t hesitate to contact us at (540) 373-5876. Also, if your furnace won’t turn on and you are not comfortable troubleshooting the problem, please contact the professionals at Robert B. Payne. We are always happy to help!