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Serving Maryland, Virginia, and Washington, D.C.

Serving Maryland and Washington, D.C.

Serving Fairfax and Loudoun Counties and the
surrounding area

Monday - Friday 7:30am - 5:30pm | Saturday 8:00am - 1:00pm. CALL FOR EMERGENCIES


Serving Maryland, Virginia,
and Washington, D.C.

Serving Maryland and Washington, D.C.

Serving Fairfax and Loudoun
Counties and the surrounding area

24 Hour Emergency Services, 7 Days a Week

Home of Mr. Heat Pump

B&B Air Conditioning & Heating Service Blog

What to Do If Your Furnace Won’t Heat


You may not have turned your furnace on for the first time this winter, but you’re coming closer and closer to that moment. If you’ve already scheduled heating maintenance in Rockville, MD, your furnace will probably come on as it’s supposed to and provide warmth for your family.

But what if it doesn’t? We don’t just mean at the start of the winter, but at any point during the season. The furnace may not come on at all, or you may get room temperature air from the vents rather than the warmth you expect. 

If your first thought is to call us to see if your furnace needs repairs, you’re off to a good start. You never want to attempt to repair a furnace yourself, as it can be dangerous. But before you give us a call or send us a message (and we’re here for you 24/7!), you can go through several basic troubleshooting steps to see if there is a simple reason you aren’t getting warm.

Step 1: Check the thermostat

Make sure the thermostat is set accurately so it will turn the furnace on. You may have it in “fan-only” mode, or perhaps someone in your house adjusted it or changed the programmed settings. If the thermostat runs on batteries, put in fresh ones to see if this gets it working again.

Step 2: Check the furnace switch

A furnace has a shut-off switch to turn it off after the heating season. You may have forgotten to turn this switch back on. You’ll find the furnace switch located next to the furnace.

Step 3: Secure the front panel

Gas furnaces have several safety features that will shut the furnace down to prevent hazards. If the front panel of the furnace cabinet is open, it will prevent the furnace from starting. The panel may be loose and unlatched, so check to see that it’s shut. 

Step 4: Check the electrical panel

Gas furnaces may use natural gas to generate heat, but they also require electricity to run several key components, such as the blower fan, the control board, and the igniter. The furnace may have tripped a circuit breaker when it tried to come on (the blower fan motor is the likely culprit) and shut down. Reset any tripped circuit breaker and try the furnace. If it trips the breaker again, the furnace probably needs an electrical repair.

Step 5: Change out a clogged furnace filter

If you’ve left the same filter in the HVAC system since summer, it’s probably so clogged up that it’s restricting the furnace’s ability to function. A clogged filter means less air is allowed to flow into the burner assembly, which can keep the burners from igniting. It can also overload the blower or make the furnace overheat. Put in a clean filter to see if this gets the furnace working again. (And remember to change the filter every 1 to 3 months through the rest of the season.)

If your furnace is still not working at this point, it’s time to call our technicians. We’ll see the furnace gets back to work ASAP.

Rely on B&B Air Conditioning & Heating Service: We are always there when you need us.

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