Why Does My Furnace Keep Blowing the Fuse?

Posted on: January 11th, 2016

Is your furnace blowing the fuse? This can be due to a number of problems that can vary greatly depending on the type of furnace you have. Electric furnaces, for example, use electricity to generate heat. There are a number of issues that could go wrong, causing the fuse to blow. On a gas or oil furnace, the causes are going to be much more limited as electricity only controls a few functions associated with the furnace.

For immediate assistance, contact your local heating and cooling contractor, or read the common causes below:



Blown fuses usually result either from an appliance putting too much strain on the fuse or by an electrical short in the system. Since some furnaces can require a lot of electricity, homeowners must ensure that they have an adequate electrical system to support the furnace. After resetting the circuit breaker and replacing the fuse, if the fuse keeps blowing, there might be an electrical short in the electrical system that supplies the electricity to the furnace. In this case, you should call an electrician.

Faulty Transformer

Sometimes the blown fuse in the furnace comes from a malfunctioning transformer. In this case, your will need a technician to come and replace the old transformer with a new one.

Insufficient Fuse Size

If the fuse in your furnace is too small and cannot handle the wattage, it can cause your fuse to blow. If this is your problem, simply replace the fuse with a larger capacity fuse that can handle the electrical demands.

Malfunctioning Thermostat Wire

If your thermostat wire touches the metal frame of the furnace, this can cause a blown fuse. When a thermostat wire touches the metal frame of the furnace, it can deliver more voltage than the wires are designed to handle. This will blow the fuse on the control board, causing the draft inducer to not start, which then stops the rest of the furnace functions from working properly.

Loose Wires

Sometimes, your furnace may seem like it has blown a fuse, but it is actually suffering from loose wire connections.  This is usually a good place to start looking for problems with your furnace as loose wires can usually be detected with a voltage meter. If loose wires are detected, they should be repaired or replaced by an electrical or HVAC technician.

How to Fix a Furnace That Keeps Blowing a Fuse

If your furnace keeps blowing a fuse and you don’t know how to fix it, you may need to call an HVAC professional to schedule a furnace repair. If you are in the Scranton, Pennsylvania area and are looking to schedule a repair, look no further than T.E. Spall & Son.

For over 25 years, we have been providing families throughout Northeastern Pennsylvania with top furnace repair service, including 24/7 emergency repair! Our heating and cooling technicians will run a diagnostic on your furnace to determine the cause of your problem and fix it right the first time—on schedule and on budget—and usually on the same trip to your home!

Call Spall at 877-591-7508 to schedule a repair or contact us online!