Why Is My Heater Not Working When My Thermostat Is On?

When the first chill of winter hits, it’s time to power up the heater for the first time in months. Unfortunately, we’ve been hearing from some homeowners that their heater is not working even when the thermostat is on. There are more than a few reasons this could be happening. Because of this, we’re sharing some pointers about what to do when your heater is not working.

(Side note: We normally refer to the heater as the furnace, but in this article we will use heater and furnace interchangeably.)

Technical Problems that Keep Furnaces from Bringing the Heat

Furnaces built after the 1990s come with a safety switch or safety shut out. This safety switch plays an important role in the overall health and safety of your home and your HVAC system. For example, if the safety switch detects that gas is being fueled into your furnace without igniting, the safety switch will turn off the system. It will also shut off your system if it’s too hot or if it detects a carbon monoxide leak. If the safety switch is triggered, you won’t be able to turn on your HVAC system until it’s checked by a professional, no matter what setting your thermostat is on.

Safety Switch

Safety Switch

If your thermostat is fully functional and you’re still unable to feel any heat coming from the vents, you may be dealing with some of these problems:

  • Dirty evaporator coils
  • Clogged pipes
  • Full air filters
  • Broken wires
  • Burnt control board
  • Dead blower motors

Whatever the issue may be, when the entire system refuses to start, homeowners need the assistance of their preferred HVAC contractor for further diagnostics on a heater not working.

There is No Gas – Heater Not Working

The majority of heaters in the United States need fuel to run properly. Many homes come equipped with a line that brings natural gas from a city supply into their home. This natural gas line can power almost all a home’s appliances including the stove and clothing dryer. The central air system itself requires several different power resources. It uses gas, electricity and even water. Consequently, it is easy to lose track of what is on and what is off. Sometimes, homeowners call AC technicians about a problematic furnace only to discover that the power breaker was off.

Gas Valve

Gas Valve in the Furnace

In similar fashion, it is common to find that the furnace has trouble finding gas to use. This can be because the gas valve is stuck or the control board is unable to communicate. In these situations, the furnace is ready for heating, but because it is unable to build a flame, it cannot proceed with the process.

The best way to check if your gas line is functional is to turn on your stove. If you can light a burner on your stove without any problem, the heater’s issue isn’t with the gas line.

The Furnace Needs Maintenance Work Done

Scheduling routine maintenance the best way to ensure the longevity and functionality of your furnace. At Service Champions, we recommend two tune-ups every year. One before spring and one before winter. During a tune-up, our expert HVAC technicians will look go through an 18-point list, ensuring no part of your furnace is overlooked. Our technicians understand that every furnace is unique and deserves unique care. During a tune-up, your technician will inspect and professionally clean every part of your system. They will also let you know if there are any small problems that need to be fixed.

Heater Not Working 02

Homeowners regularly underestimate how important and effective furnace maintenance can be. Just one appointment clears out residue, buildup and debris that can hamper energy efficiency and heating quality.

With furnace maintenance:

  • Motors spin without resistance
  • Burners hold fires without using excess gas
  • The furnace experiences less stress
  • There is less damage to parts such as motors and wires
  • The central air system lasts longer and works better

One thing to keep in mind is that there is no wrong time to schedule a furnace tune-up. Did you forget until March? We do furnace tune-up during March! Time doesn’t matter, the maintenance is. Either call the number at the top of the screen to speak with our friendly customer representatives, or click here to schedule a tune-up online.

Did You Forget to Change Your Air Filter?

After scheduling routine maintenance, the next best thing you can do for your HVAC system is regularly check and change your air filer. A dirty air filter could be the root of your furnace problems.

Sc Airfilter 01

When a filter gets too full, it can greatly restrict any air flow. Meaning treated air is trapped in your HVAC system. Instead of nice warm air, your home only has the ambient air that can make it through the clogged filter. Also, a dirty air filter can make your utility bill skyrocket. When treated air is trapped by the air filter, your heater works twice as hard to produce the same amount of air. A dirty air filter could also be the cause of short cycling.

Is Your Furnace Short Cycling?

Your furnace and air conditioner both run in cycles. A cycle starts when your HVAC system wants to send temperature treated air in your home and stops when your home reaches the setting programmed into the thermostat. Your system’s cycle normally lasts about 15-20 minutes. If you notice your furnace short cycling, it could be an indicator of larger problems.

Oftentimes, your furnace short cycles if:

  • The furnace itself is overheating
  • The air filter is too dirty and too full of debris
  • Your flame sensor isn’t working
  • The thermostat is in the wrong spot
  • Your Furnace is too big for your home

Funace Old 01

Our Happy Money Guarantee

At Service Champions, you only pay when you are happy. We instituted a policy when we first opened our doors, nearly 20 years ago, that if a customer didn’t like the job we did, that job was free. We still stand behind that promise today. If you don’t like your service, it’s free.

Perfect Your Furnace with Service Champions

Is your heater not actually doing its job? Our air experts are on hand and ready to help with any issue you may have. We are the only Diamond Certified plumbing and HVAC company in Southern California. If you live in Los Angeles, Riverside, Or Orange county, schedule an appointment today. Simply call the number at the top of the screen or click here to book online.