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No Heat…Now What?

January 14, 2015 No Comments

Handy Dandy No-Heat Troubleshooting Checklist

If you notice that your gas furnace is not providing heat, chances are pretty good that you will need the assistance of an HVAC contractor, like Horizon Services. However, there are some common troubleshooting guidelines you should follow prior to calling a professional service technician.



In this article, Horizon Services experts share our most helpful no-heat checklist so you can identify and resolve common problems with your non-functioning heating system.

Thermostat Check

  • Is the system selector switch in the “HEAT” position?
  • Is the temperature set at least 3 degrees above current room temperature?
  • If your thermostat is electronic, are the batteries charged? Is the display showing?

For Forced Air Furnaces Only: If your thermostat has a switch to control the furnace fan, switch the fan “ON”. (This switch will usually be located at the bottom of the thermostat, closer to the left side and will be marked “ON” and “AUTO”.) Listen to hear the furnace fan coming on. If you cannot hear the fan, go to one of the supply registers and see if you can feel any air coming out. If the fan is not running, there may be no power to the furnace.

If the thermostat is set properly, the next step is to check to see that there is power to the furnace.

Electrical Check – Furnace

Some heating systems also have emergency cut-out switches that are activated when a door or service panel is removed. Often the furnace door is not replaced properly after a filter cleaning and the cut-out switch will prevent the furnace from coming on. Check to make sure all access doors are properly secured and fitted.

Your heating system may be equipped with an emergency shut-off switch for the furnace. If your system is so equipped, locate it and make sure it is turned ON. In most homes, the emergency shut-off switch looks just like a regular light switch and will be located on the side or close to the furnace. Sometimes there is a second Red Emergency Toggle Switch that is typically located at the top of the basement stairs. It is quite common for this switch to be turned OFF accidentally. If is turned OFF make sure to turn it back into the ON position. if the switch is ON, but the fan still doesn’t operate, proceed to the Electrical Check – Panel Box.

Electrical Check – Panel Box

Locate the breaker or fuses in your home’s main electrical panel for both the furnace and air conditioning unit. Make sure the breakers are not tripped or the fuses are not blown.

  • If your home has breakers, check to see if any are tripped. If a breaker has been tripped it will be in a position that is between ON and OFF. Reset the breaker (turn all the way OFF, then back ON).
  • If your home has fuses, check to see if the fuse for the furnace is blown. If so, replace it with the SAME SIZE AND TYPE of fuse. Do not increase the size of the fuse.
  • Warning: If a breaker keeps tripping or a fuse keeps blowing, you should contact a qualified service technician to inspect your system to determine why you are having problems.

Ignition Check

If your unit seems to be operating, but not producing any heat, the furnace may not actually be firing. If this is the case check the following:

  • Do you have fuel? If your unit is oil, or propane fired, check the level of fuel in the tanks. If you ran out of fuel, order some more, and now your furnace will not start, your unit may have to be reset. Some systems have a red reset button on the burner. Other systems can be reset by turning system power off then back on. If it is oil-fired, the fuel pump may need to be primed. For assistance, please ask your Horizon Services’ technician.
  • If you have an older gas furnace with a standing pilot look inside your furnace to see if it is on. If not, follow the instructions on the furnace to re-light the pilot. If after following the instructions, the pilot will not light or stay lit, call your Horizon Services’ technician.

Other Common Heat Related Problems

  • A completely clogged air filter can cause a no heating problem.
  • Broken or extremely loose fan belt.
  • Bound or tight blower motor.
  • Bound gas inducer motor could be stuck.
  • Broken gas igniter.

If your HVAC unit comes on and stays on, you’re probably okay. If it comes on for about 90 seconds and then quits, or if it doesn’t come on at all, call Horizon Services to schedule a service call with one of our knowledgeable technicians.


Contact Horizon Services

If you are ready to install or replace a heating system, our friendly and experienced team of Comfort Specialists can help. They’ll take the time to study your home, understand your requirements, show you all of your options and assist you with finding the quality home comfort system that best meets your family’s needs and budget.


Related Information from Horizon Services…




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