Skip navigation

We are hiring. Training available. Great benefits. Apply Now

Serving the Greater Lansing & Grand Rapids Areas


A-1 Mechanical Blog

Why Won’t My Furnace Turn On?


One of the biggest issues Grand Rapids area homeowners face during the winter is a broken-down furnace. Several issues can cause a furnace failure – some may be quickly solved through troubleshooting, while others require professional repairs. When you’re faced with a furnace that won’t turn on, here are the most common reasons why and what to do about them.

1. Wrong Thermostat Settings

The first thing to do is check your thermostat to see if it’s operating or set correctly. Your thermostat is the controller of your furnace’s operation, signaling it to fire up when indoor air is too cold and shut down once proper indoor temperatures are reached. If the thermostat isn’t set correctly, it won’t communicate properly with your furnace, resulting in furnace problems, including a unit that won’t turn on when it’s expected to.

  • Check the thermostat to make sure it’s set to HEAT.
  • The set temperature should be higher than the current room temperature.

2. No Power

All components of the heating system need to have power for the furnace to work. If there’s not a power outage affecting your home, check individual switches and power sources to ensure every system component is properly powered.

  • If the thermostat has a blank display or you cannot adjust it, the unit’s batteries may be dead. Replace them with a fresh set. If the thermostat is hardwired, check the circuit breaker that controls its circuit. If the breaker has tripped, reset it to restore power to the thermostat.
  • Check the circuit breakers that deliver electricity to the furnace. If the circuit breakers have tripped, reset them.
  • Check the on/off switch located on or near your furnace, and make sure it is set to the ON position.
  • If you own a natural gas furnace, make sure the gas valve is open to let the system receive fuel.
  • For oil or liquid propane furnaces, check your fuel tank to verify there is enough fuel for heating system operation. For oil tanks, keep the fuel volume above four inches; for liquid propane tanks, order a tank refill before the tank volume dips below 25 percent.

3. Pilot Light Is Out

While modern furnaces use electronic ignition, some older furnaces still use pilot lights. If the pilot light goes out due to a draft or system issue, you’ll have a furnace that won’t be able to create heat.

  • Find the pilot light assembly, which is usually located toward the furnace’s bottom. See if your furnace flame is burning or if it is out.
  • If the pilot light is out, you’ll need to relight it. First, stop any drafts that could’ve caused the pilot to extinguish. Turn the pilot switch off for at least five minutes to allow any gas to dissipate.
  • When ready, follow the instructions in your furnace’s owner’s manual to relight the pilot.
  • Once the pilot is relit, watch to see that it burns a strong blue flame and does not extinguish again. If it does go out, there could be an issue with a thermocouple. If the flame is weak and yellow, there could be dirt or other debris clogging the air intake. Call your HVAC technician to assess and repair the system.

4. Dirty Air Filter

Dirty filters can cause heating systems to overheat because they restrict air flow. If this occurs, you’ll notice that your furnace isn’t turning on – the system’s safety controls shut down operation to allow the equipment to cool.

  • Remove the faulty or dirty filter, and replace it with a new one. Be sure to use the same size air filter, and insert it into the filter cabinet in the proper direction.
  • Check filters monthly during the winter and change them as needed – it’s often necessary to replace filters more frequently this time of year because of increased heating use.

5. Blower Motor Issue

If the blower motor malfunctions, your forced air furnace may run but your home will not receive any heat. Inspect the blower to see if the issue can be resolved. You may need to contact a qualified HVAC company for repair services.

  • Shut off power to the furnace, and remove the access panel to the blower chamber. Check for any debris that may be blocking the fan blades or heavy dirt that could be clogging up the motor. Clean as necessary.
  • Check the belt linking the motor and fan. If it has slipped or become loose, you may be able to tighten and reposition it. If the belt has broken, it needs to be replaced.
  • If you cannot find the blower motor issue, it’s time to call for professional furnace repair.

Get Heating Help from A-1 Mechanical

Don’t let a furnace that won’t turn on compromise the comfort of your family this winter – call A-1 Mechanical for fast, reliable furnace repair. Our technicians will get to the bottom of furnace issues and make repairs to help you avoid facing a furnace that’s not turning on for the remainder of the season. Contact us today to get your furnace working properly again in no time.

Comments are closed.