When Your Heater Stops Working: What to Do First
To fix heater in house issues, start with these five essential checks:
- Verify thermostat settings – Ensure it’s set to “Heat” and the temperature is higher than the current room temperature
- Check the air filter – A clogged filter is the most common cause of furnace problems
- Inspect the circuit breaker – Look for tripped breakers or a furnace power switch that’s been turned off
- Ensure vents are open – Blocked or closed registers restrict airflow and reduce heating efficiency
- Confirm gas supply (for gas furnaces) – Make sure the gas valve is open and parallel to the pipe
It’s a scenario every homeowner dreads: you wake up on a frigid morning to find your house is freezing. The thermostat says it should be 72°F, but you can see your breath. Your heater has stopped working, and you’re left wondering what to do.
The good news? Many heater failures have simple fixes you can handle yourself before calling a technician. According to HVAC professionals, dirty filters alone account for the majority of furnace problems—and changing one takes less than five minutes.
The research is clear: a comprehensive understanding of your heating system can save you hundreds of dollars and hours of discomfort. While some repairs require professional expertise (especially anything involving gas lines or electrical components), basic troubleshooting is well within reach for most homeowners.
This guide will walk you through the most common heater problems and their solutions, starting with the simplest fixes and progressing to more advanced troubleshooting. We’ll also help you recognize when it’s time to stop and call in the experts—because safety always comes first.
First Things First: 5 Simple Checks Before You Panic
When your heater suddenly stops working on a freezing Colorado or Utah morning, those first few minutes can feel pretty desperate. Your instinct might be to immediately call for help, but hold on—take a deep breath first.
Here’s something that might surprise you: most heater problems have surprisingly simple causes. We’ve been in this business long enough to know that a good chunk of emergency calls get resolved with basic fixes that homeowners can handle themselves. Before you spend money on a service call, let’s walk through five quick checks that solve the majority of heating issues.
These simple steps will help you fix heater in house problems related to thermostat settings, dirty filters, power interruptions, blocked airflow, and gas supply. You might just have your heat back on in minutes.
1. Check Your Thermostat Settings
Your thermostat controls everything about when and how your furnace runs. It’s also the source of more false alarms than you’d believe.
Start with the obvious: make sure it’s set to “Heat” mode, not “Cool” or “Off.” We know it sounds too simple, but during those awkward spring and fall days when temperatures swing wildly, it’s easy to forget which mode you left it in. Next, check that your temperature setting is at least 5 degrees higher than the current room temperature. If your home is already 70°F and the thermostat is set to 68°F, your furnace is doing exactly what it should—nothing.
Dead batteries are another sneaky culprit. If you have a digital thermostat with a blank screen or dim display, pop it open and swap in fresh batteries. It takes about 30 seconds and might save your day.
Programmable thermostats can be wonderful, but they can also work against you. Check if yours is following a schedule that’s overriding what you want. Most have a “Hold” button that lets you bypass the program temporarily. If you’re comfortable doing so, you can also gently remove the thermostat cover and look for dust buildup or loose wires. A soft brush can clean away dust, but if you spot broken or disconnected wires, that’s a job for a professional.
Still having issues? Our team can help with thermostat repair and installation to get your system back on track.
2. Inspect the Furnace Air Filter
If we earned a nickel every time a dirty air filter was the entire problem, we’d retire early. It’s hands-down the most common reason furnaces stop working—and also the easiest to fix.
Think of your furnace trying to breathe through a pillow. That’s what happens when the air filter gets clogged with dust, pet hair, and debris. Your system can’t pull in enough air, so it works harder and harder until it overheats. Modern furnaces are smart enough to shut themselves down before damage occurs, which means you’re left without heat.
The warning signs are pretty clear: weak airflow from your vents, the blower running but no air moving, or your furnace cycling on and off repeatedly. All of these point to a restricted filter.
Finding your filter is easy. Look in the return air duct just before the furnace, or inside the furnace cabinet itself. Pull it out and hold it up to a light. Can you see through it? If not, or if it looks like it’s wearing a fur coat, it needs replacing immediately. Note the size printed on the frame (something like 16x25x1) before you head to the store.
When you install the new filter, pay attention to the arrow printed on the frame—it should point toward the furnace, showing the direction of airflow.
Regular filter changes don’t just keep your furnace running—they also dramatically improve your home’s air quality. Check out our guide on improving indoor air quality for more ways to breathe easier.
3. Verify the Power Supply
Sometimes the answer is almost embarrassingly simple: your furnace isn’t getting electricity. We’ve driven across Denver and Salt Lake City to find that someone accidentally flipped the wrong switch.
Head to your electrical panel and look for a tripped circuit breaker. Furnaces usually have their own dedicated breaker. If you find one sitting in the middle position or clearly flipped to “off,” switch it all the way off first, then firmly back to “on.” If it immediately trips again, stop—that signals an electrical problem that needs professional diagnosis.
Next, hunt down the furnace power switch. This usually looks exactly like a regular light switch and sits on or near the furnace itself. Make sure it’s in the “on” position. It’s often mounted on the wall nearby, and more than one person has mistaken it for a basement light switch.
Here’s one more thing to check: many furnaces have a safety switch on the blower compartment door. If that door isn’t completely closed and latched, the furnace won’t run. Give the door panel a firm push to make sure it’s seated properly.
4. Ensure All Vents and Registers Are Open
You might think closing vents in unused rooms saves energy, but it actually works against you. Your heating system is designed to move a specific amount of air through your home. When you close too many vents, you create pressure imbalances that strain your blower motor and can even cause duct leaks.
Walk through your house—yes, every room—and check that all your supply registers (where warm air comes out) and return vents (where air gets pulled back in) are fully open. Look for furniture pushed up against vents, curtains hanging over them, or rugs covering floor registers. These innocent obstacles can seriously restrict airflow.
If certain rooms in your Highlands Ranch or Provo home are always colder than others, blocked vents are often the reason. Opening everything up allows your system to distribute heat the way it was designed to, which means better comfort and lower energy bills.
5. Check the Gas Supply (For Gas Furnaces)
If you have a gas furnace that’s not producing heat, the gas supply is the next thing to investigate. This check requires careful attention and a healthy respect for safety.
Start by locating the gas valve on the pipe leading to your furnace. The handle position tells you everything: when it’s parallel to the pipe, gas is flowing. When it’s perpendicular (making a “T” with the pipe), gas is shut off. Make sure it’s parallel. Sometimes after maintenance work or a long vacation, someone turns it off and forgets to turn it back on.
If you have an older furnace, check whether the pilot light is lit. You should see a small blue flame. If it’s out, you’ll need to relight it—we’ll cover that process in detail later in this guide. Newer furnaces use electronic ignition and won’t have a continuously burning pilot light.
For homes that use propane, especially in areas like Ogden or Sandy, check your tank level during peak heating season. An empty tank means no heat, plain and simple.
Critical safety warning: If you smell gas—that distinctive rotten egg odor—stop everything immediately. Don’t flip switches, don’t light matches, don’t investigate further. Turn off the gas at the main valve if you can do so safely, get everyone out of the house, and call your gas company and us from outside. Gas leaks are life-threatening emergencies that require immediate professional response.
How to Fix a Heater in Your House: A Step-by-Step Guide
Once you’ve completed the initial basic checks, and your heater is still giving you the cold shoulder, it’s time to dig a little deeper into specific troubleshooting steps. This section will guide you through more targeted solutions, distinguishing between gas and electric systems and addressing common issues like ignition problems and clogged condensate lines.
Troubleshooting Gas vs. Electric Heaters
Before you can effectively fix heater in house problems, you need to know what you’re working with. Gas and electric furnaces might both warm your home, but they’re as different under the hood as a gas grill and a toaster oven.
Gas furnaces are the most common type in areas like West Jordan and Aurora. They burn natural gas or propane to create heat. When your thermostat signals for warmth, a gas valve opens, and an ignition system lights the fuel. The flames heat up a metal component called a heat exchanger, which warms the air without letting combustion gases into your home. A blower then pushes this heated air through your ductwork. The combustion byproducts exit safely through a flue or exhaust vent.
Electric furnaces take a completely different approach. They use electric heating elements that work much like the coils in your oven. When heat is needed, electricity flows through these elements, causing them to glow red-hot. Air passes over these elements and gets warmed before the blower circulates it throughout your house. There’s no combustion, no gas lines, and no exhaust venting required.
Understanding which system you have is crucial because the troubleshooting steps differ significantly. Gas furnaces have issues related to pilot lights, gas valves, and flame sensors. You might need to check if the pilot light is lit, ensure the gas valve is open, or clean a dirty flame sensor that’s preventing the burners from staying on.
Electric furnaces, meanwhile, deal with problems involving heating elements and sequencers. A heating element can burn out just like a light bulb, causing reduced heat output or no heat at all. The sequencer is a component that turns the heating elements on in stages to prevent overloading your electrical system. If it fails, your furnace might not heat properly or could trip your circuit breaker repeatedly.
If you have a gas furnace and smell that distinctive rotten egg odor, stop troubleshooting immediately. That’s the scent added to natural gas to alert you to leaks. Evacuate your home and call your gas company and a professional from a safe location.
How to fix heater in house issues related to ignition
Ignition problems are one of the most common reasons gas furnaces fail to produce heat. The good news is that some ignition issues are surprisingly simple to resolve, while others require a professional touch.
Older furnaces with standing pilot lights have a small flame that burns continuously. This pilot light ignites the main burners when your thermostat calls for heat. If you peek through the viewing window on your furnace and don’t see that little blue flame, your pilot light has gone out. This can happen due to drafts, a dirty pilot orifice, or a faulty thermocouple.
Relighting a pilot light isn’t as intimidating as it sounds. First, locate your furnace’s instruction label, usually attached to the inside of the access panel. Turn the gas valve to the “off” position and wait at least five minutes to allow any lingering gas to dissipate. Then turn the valve to “pilot,” press and hold the reset button, and use a long lighter to ignite the pilot. Keep holding the button for about 30 seconds after the pilot lights to allow the thermocouple to heat up. Release the button, and if the pilot stays lit, turn the valve to “on.” If the pilot won’t stay lit after several attempts, there’s likely an issue with the thermocouple or gas supply that requires professional repair.
Modern furnaces use electronic ignition systems instead of standing pilot lights, which are more energy-efficient since they don’t burn gas continuously. The most common type is a hot surface ignitor, which looks like a small ceramic element. When your thermostat calls for heat, this ignitor glows bright orange for several seconds before the gas valve opens. The combustion process then begins, and your furnace produces heat.
Hot surface ignitors are fragile and can crack or wear out over time, especially in older systems. If you hear your furnace attempting to start but the burners never light, a failed ignitor is a likely culprit. While you can visually inspect the ignitor through the viewing window, we don’t recommend replacing it yourself unless you’re comfortable working with your furnace’s electrical components. These ignitors are delicate and easy to damage during installation.
Clearing a Clogged Condensate Drain Line
If you have a high-efficiency furnace (typically 90% AFUE or higher), it produces condensation as part of the heating process. These furnaces extract so much heat from the combustion gases that water vapor condenses into liquid, just like water droplets forming on a cold glass of lemonade on a hot day.
This condensate needs somewhere to go, which is where the drain line comes in. A small plastic tube carries the water away from your furnace to a floor drain, sump pump, or outside drain. When this drain line gets clogged with algae, mold, or debris, water backs up and can trigger a safety switch that shuts down your entire system.
The first sign of a clogged condensate line is often water pooling around the base of your furnace. You might also notice your furnace shutting down unexpectedly, especially if it’s been running fine but suddenly stops. Some furnaces have a clear condensate trap that allows you to see if water is backing up.
To clear a clogged drain line, first turn off your furnace at the thermostat and the power switch. Locate the condensate drain line (usually a 3/4-inch white PVC pipe) and the condensate trap. Many traps can be unscrewed by hand for cleaning. Remove any visible debris, then flush the drain line with a mixture of one cup of bleach or white vinegar to one gallon of water. Pour it slowly through the drain opening and let it sit for 30 minutes before flushing with plain water.
If water still won’t drain properly, the clog might be further down the line and may require a wet/dry vacuum to suction it out from the drain end, or a professional cleaning. Regular maintenance can prevent these clogs from happening in the first place. For more information on keeping your system running smoothly, check out our guide on Preventative Measures to Avoid Furnace Repair.