Why is my heater not working is the question behind most of the calls we take once the weather turns.
As cooler weather approaches, you might wonder whether or not your heating system needs to be cared for by a professional. Your system is still working well enough, so it should have no problem heating your home when it’s cold outside, right? Not really.
If your heating system is showing any of the following signs of trouble, then you should consult a competent heating and cooling professional about the well-being of your equipment.
What this covers
- Signs you need heating repair
- My heater won’t turn on at all
- When to stop troubleshooting and call
- Frequently asked questions
Signs You Need Heating Repair
Your Electric Bill is Higher Than Normal
Fuel prices can increase with minimal warning, but not every expensive electricity bill is the result of cost hikes. If your energy bill has spiked unexpectedly and your rates haven’t changed, then your heating system might be the culprit. The harder your heater has to work to keep your home warm, the more energy it will burn. A professional will potentially be able to get your unit running efficiently again.
Your Heating System is Making Strange Noises
Even if your system is still producing heat, it might not be doing so as quietly as it should. Clanking, rattling, banging, screeching, grinding, and other similar noises may occur when your heater needs to be repaired by a professional. Grinding or squealing often points to the blower motor, and if you ignore these sounds, then your heating system might fail altogether, requiring a costly replacement.
Your Heater Has Needed Many Repairs
If you realize that you’ve had to have many parts replaced or repaired in the recent past, then your heating system might have a larger overall problem. A capable professional will be able to check your heating equipment for significant issues.
Your Burner Flame Is Yellow Instead of Blue
Your burner flame is supposed to burn blue, so if it turns yellow, this is a sign of a serious problem. A yellow burner flame indicates the presence of carbon monoxide, which is a highly toxic gas that can cause people to experience flu-like symptoms and even death. On a gas furnace, this sometimes points to a cracked heat exchanger, which is one of the few faults serious enough to shut a system down for good. If your burner flame turns yellow, you need to contact a trustworthy HVAC contractor immediately.
Your Thermostat Requires Frequent Adjustment
Ideally, you should be able to set your thermostat at your preferred temperature and then go about your daily routine. If you have to adjust your thermostat multiple times a day to heat your home to the right temperature, then your heating system may have a problem. This condition will likely worsen over time, so you should have a professional fix your heating system if it occurs.
Your Heating System Experiences Short Cycles
Your heater should cycle relatively regularly until your home gets to the temperature on the thermostat. If its cycles are shorter than that, it’s an issue known as short cycling. It has many potential causes, but short cycling puts extra stress on your system and consumes more energy than your system typically does.
Your Air Quality Is Poor
Bad air quality can be another sign that your heating system is having problems. If your home has become stuffy, dusty, or hazy, then your heater may need to be serviced. A dirty air filter is often the starting point, since restricted airflow pulls more dust through the rest of the HVAC system. Poor air quality can cause increased allergies, respiratory issues, and other health problems, so you should let a professional fix your heater and improve your air quality.
Your Heater Can’t Evenly Heat Your Home
If some rooms in your house are cooler than others, then your heater might have an issue that needs to be addressed by a professional. Uneven heating could be a sign of ductwork troubles, poor insulation, and more. If a vent is blowing cold air while others run warm, that usually means airflow rather than a heating fault. Unless you want to avoid certain parts of your home during cooler weather, you should let an HVAC technician get your heater working properly again.
Heater Not Turning On At All: Quick Things to Check First
Total failure is a different problem from the warning signs above, and it’s the one that sends most people searching. When a furnace won’t turn on, there are four things worth checking before you book anything. We’d rather you find the answer here than pay for a visit you didn’t need.
Around here, heaters sit unused from roughly March through November. A system that worked fine last winter can refuse to start on its first cold night simply because it’s been idle for eight months. That’s normal, and several of these checks exist because of it.
1. Check the thermostat
It sounds obvious, and it’s the most common reason we find for a heater not turning on. Make sure it’s set to Heat rather than Cool or Off, and that the temperature is set several degrees above the current room temperature. A system won’t fire for a one-degree difference.
Then change the batteries. A thermostat with dying batteries can keep its display lit while losing the ability to signal the furnace. If yours is hardwired with no batteries, check whether the display is on at all.
2. Check the circuit breaker
Go to your electrical panel and find the circuit breaker for the furnace or air handler. A trip sometimes doesn’t look obviously off, so switch it fully to Off and then back to On.
If it trips again straight away, stop. Something is drawing more current than it should, and repeatedly resetting a breaker on a fault is how small problems become fires.
3. Check the furnace power switch
Most furnaces have their own switch nearby, and a furnace won’t turn on if that switch has been flipped off. It looks exactly like an ordinary light switch, which is why it gets switched off by accident during cleaning, painting, or attic work.
Check the service panel door too. Many furnaces have a safety switch that cuts power if the door isn’t seated properly.
4. Check the air filter
A clogged air filter will choke airflow badly enough that the system overheats and shuts itself down on a safety limit. In Southern California, a furnace filter that sat through a dry summer is often worse than people expect.
Pull it out and hold it up to a light. If you can’t see light through it, replace it, then wait about thirty minutes for the system to reset before trying again.
When to Stop Troubleshooting and Call a Professional
Why would a heater suddenly stop working after a season of running fine? Usually a fault in the parts you can’t safely reach: ignition components, the gas valve, high-voltage wiring, or sealed assemblies inside the unit. Those need a technician.
So if you’ve worked through those four checks and the heater still won’t start, stop there and book a service call.
Some situations skip the troubleshooting entirely. Call right away if any of these apply:
- You smell gas. Leave the house first, then call from outside
- The burner flame is yellow rather than blue
- The breaker trips again after you reset it
- The system starts and shuts off repeatedly
- Anyone in the house has unexplained headaches, nausea, or flu-like symptoms that clear up when they leave
That last one is worth taking seriously. Carbon monoxide symptoms look enough like a winter bug that families put them down to the season
Checked everything and it still won’t start?
Our HVAC technicians will diagnose it properly rather than guess.
Service All-Stars has been working across Bellflower, Anaheim, and the
surrounding cities for two decades.
Schedule Heating Repair Service
(833) 899-8010
Frequently Asked Questions
Why is my heater running but not heating?
Usually a thermostat set to Fan rather than Auto, which circulates air without calling for heat. Beyond that, the common causes are a dirty air filter restricting airflow, a failed ignition component or flame sensor on a gas furnace, or duct leaks losing warm air before it reaches the rooms.
Why would a heater suddenly stop working?
Most sudden failures come down to a power issue, a safety shutoff, or an ignition failure. A tripped circuit breaker, a flipped furnace switch, or a clogged air filter triggering a limit switch account for a large share of the calls we take. Ignition and sensor faults need an HVAC technician.
What should I do if my heater won’t turn on?
Work through the four checks above: thermostat mode and batteries, circuit breaker, furnace power switch, and air filter. If none of them resolves it, book a repair service rather than going further, since the remaining causes involve gas and high-voltage parts.
Why is my furnace blowing cold air?
Common reasons include a thermostat set to Fan instead of Auto, a pilot light or ignition failure meaning the burners never fire, or a system that overheated and shut the burners down while the blower keeps running. If the blower is moving air but nothing is warming it, that’s the pattern to look for.
How long does a heating repair take?
Most repairs are finished in one visit, though a part that has to be ordered adds time. We’ll tell you which situation you’re in before starting work.
Heating Repair in Bellflower and Across Southern California
If you spotted any of the signs above, sooner is cheaper than later. Small faults on a heating system rarely stay small, and the ones that seem harmless are usually the ones that fail on the coldest night of the year.
Our heater repair service covers gas furnaces and heat pumps across Anaheim, Bellflower, Lakewood, Cerritos, Downey, and Buena Park. If your system is still running fine and you want to keep it that way, heating maintenance is the cheaper route.
Service All-Stars is licensed in California, CSLB #1048799.
