3 Fixes for a Furnace That Has Stopped Working

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It is never fun to come home and expect a nice, toasty house, only to discover interior temperatures hovering barely above exterior temperatures. Clearly, your furnace has stopped working. Before you rush to your phone to call in an HVAC technician, you can benefit, both in terms of money and time, to try to fix your furnace by yourself. While furnaces are complex, with deep repairs usually best left in the hands of licensed technicians, there are a number of easy-to-do fixes that you should try to do by yourself. In some cases, you may have the furnace up and running sooner than the technician would have arrived.

Check That the Furnace Is Drawing Power

When your bathroom fan, kitchen microwave, or dining room light fail to operate, your natural instinct might be to check the circuit breaker on the electric service panel as it may have tripped. Flipping a circuit breaker back on is the instant solution for many household problems, including some furnace problems. Both electric and gas furnaces are electrically controlled.

How to Fix It

  1. Locate your electric service panel.
  2. Open the door.
  3. Find the circuit breaker that controls the furnace. Your furnace may have two circuit breakers, not one. They should be next to each other, top and bottom, or it may be in the form of a single, jumbo-sized breaker.
  4. Flip the circuit breaker backwards (toward the outside), then flip it inward. It should snap into place, activating the furnace.
  5. Another way to see if your furnace is receiving power involves the toggle switch on the side that allows you to manually turn on fan-only operations. Flipping this switch and listening for the fan turning on is one way to double-check that the furnace is receiving power. It verifies that, even if the burner part of the furnace is not operable, other parts are working.

Check the Thermostat

Is the thermostat properly triggering the furnace? This is one of those solutions that seems all too simple. But sometimes a child, guest, or even you may interfere with the workings of your thermostat. Sometimes, thermostats go bad or become disconnected.

How to Fix It

  1. Check to see if the automatic clock on the programmable thermostat is accurate.
  2. See if the batteries need changing. Many thermostats, though, operate off of the low-power current from the wire that attaches to the thermostat, so they will have no batteries.
  3. Unscrew the thermostat from the wall gingerly. Ensure that the wire coming out of the wall is securely attached to the thermostat.
  4. If you find the programmable thermostat too difficult to understand, switch it out for an older style dial analog thermostat, if only for testing purposes.

Fix the Condensate Pump or Empty the Pan

You may have owned your furnace for years or even a decade or longer and have wondered about a mysterious sound that your furnace frequently emits. This faint buzzing sound that sounds similar to a water pump for an aquarium or water feature is often, but not always, heard after a long heating cycle. If you have thin walls and floors, you may hear it in other rooms than the furnace room. You should be able to hear this sound when you are in the furnace room.

This sound is normal and it is indeed a pump. After long cycles, condensation is drawn from the air and deposited into the furnace. This condensation builds up so copiously that it has no time to evaporate back into the air. Unlike a window unit air-conditioner, for example, which is located on the home's exterior and can deposit the water onto the ground, furnaces are usually centrally located within a home; there is no place for the water to exit on its own. The condensate pan collects the water and its attached condensate pump expels it out of the house.

How to Fix It

  1. Turn off all circuit breakers controlling the furnace.
  2. Look for the rectangular-shaped box attached to the side of the furnace.
  3. The pump may be hard-wired into the furnace or may be plugged into a GFCI outlet nearby. If the latter, reset the GFCI outlet. If the GFCI will not reset, replace it.
  4. Check the tube that runs from the condensate pump to the outside and make sure that it is not pinched or blocked.
  5. Open the lid to the condensate pan (usually removing the condensate pump in the process). Check to see if the draw tube is still at the bottom and is not plugged.
  6. If the condensate pump pan is overly full and possibly leaking on the floor, the automatic switch on the pump that triggers when water level rises is not working. Manually flip that switch back and forth a few times to loosen it.
  7. If the condensate pump is not working, replace it entirely. Condensate pumps are inexpensive and easy to replace. If the pump is hard-wired into the furnace, though, you may wish to hire an electrician for this step.