Blown Furnace Fuse: What You Can Do

Has your home furnace blown a fuse or two? While you may think that a tripped breaker or a blown fuse may not be a big deal, there are several situations where you may risk complex failures unless you address the reason why your furnace keeps blowing fuses.

Since some of these reasons can be quite serious, it is advisable to reach out to furnace repair professionals if your heating system in San Diego keeps tripping breakers. In the meantime, keep reading to learn about the common culprits of blown furnace fuses.

Why would a furnace fuse blow?

Here are some of the most common reasons why your furnace may be blowing fuses:

Damaged wiring
Poorly connected and/or damaged wires can cause your furnace to short circuit and blow a fuse. If this is the case, it is generally best to let professionals inspect the wiring and resolve the issue.

Dirty air filters
A lack of maintenance can lead to dust and debris accumulating on the air filters. Unless the air filters are regularly cleaned or replaced, the grime may migrate to the blower motor, causing it to overheat and lead to a high limit failure. The best way to prevent this issue is to have your furnace maintained on a regular basis.

Thermostat metal frame
Thermostats surrounded by metal frames have been known to cause furnaces to blow fuses. This happens when the wiring inside the thermostat touches the metal frame, creating voltage issues and potentially blowing the control board. If this happens, you’ll have to reach out to professionals to fix the problem before being able to use the furnace again.

Worn or faulty components
When failing or faulty, the following furnace parts may cause the unit to short circuit:

  • A failing furnace capacitor causing intermittent electrical issues
  • A faulty furnace blower motor may cause short circuits
  • A worn or faulty furnace transformer can also cause a system failure
  • Valves that can’t properly open and close may cause your furnace to overheat or stop working

If you suspect any of these furnace issues, don’t hesitate to contact your HVAC professionals of choice if you wish to prevent unnecessary damage to your unit and expensive repairs.

How do I know if my furnace fuse is blown?

Before you go looking for a new fuse, you should make sure that you’re actually dealing with a blown fuse and not some other issue. Checking your furnace fuse is a relatively simple procedure that won’t take much of your time. Still, reaching out to professionals to inspect your furnace may be the better cause of action if this isn’t the first time you’ve had this problem with your furnace.

Start by making sure that the furnace thermostat is set to “heat” and a suitable temperature. If so, check the power switch and see if it’s in the “on” position. If both of these are in order, it is time to check the breaker or fuse box.

Where is the fuse on a furnace?

In order to check and replace the fuse, you’ll first need to locate it. Hopefully, you already have an idea where the electrical panel is located and whether you have a circuit breaker or a fuse box. If you don’t, check your garage, basement or closet and try to find a grey metal box.

Circuit breakers
If your home has a circuit breaker box instead of fuses, each circuit breaker should be connected to rooms in your home or individual appliances. Your furnace most likely has a dedicated circuit of its own. The breakers are usually labeled, but if not, it will be quite easy to tell which breaker has tripped, as it will probably be in the opposite direction of the others.

Before you attempt to restore power, dry off your hands completely and flip the tripped circuit breaker with one hand. This should restore the power unless you’re facing a more serious issue with your furnace.

If your furnace has a fuse, it will probably be located in the control box with the blower. BIf you can’t locate it, the transformer may have burned up and will need to be replaced.

Once you’ve located the fuse, check its wires to see if they’re broken or look for signs of discoloration or cloudiness. If so, you have a blown fuse that will have to be replaced. You can also use a multimeter to check if the fuse is blown. A good fuse normally has nearly zero resistance (in ohms), whereas a blown fuse will show no reading.

How do I change a fuse in my furnace?

If you’ve determined that your furnace fuse is indeed blown, you’ll most likely be able to replace it quite easily. However, you’ll have to make sure to purchase a fuse that has the same wattage rating as the previous one. Check the manufacturer’s instructions manual to find information on how to properly replace the furnace fuse.

While most homeowners will be able to successfully replace a blown fuse, it is crucial that you contact experienced HVAC technicians to inspect your furnace system if it keeps tripping breakers or blowing fuses. This is because there may be a more complex issue causing the fuses to blow that might result in serious damage to your unit if not addressed properly.

Hire the favorite furnace repair experts in San Diego

Action Air Conditioning, Heating & Solar is your go-to choice if you’re dealing with a blown furnace fuse or any other HVAC issue in your home. Our qualified and dedicated technicians can help ensure your comfort across San Diego, so don’t hesitate to get in touch with us whether you live near SeaWorld or anywhere else in the area.

With years of experience in the field, our team is able to resolve all kinds of HVAC issues, however large or small, using time-tested equipment and methods. We can also install a brand new high-efficiency furnace for you or routinely maintain your existing system to keep your home cozy all year round. Contact us today.


“Complete HVAC system install was done – very professional and clean workmanship. The techs were very communicative during the whole process. I am very pleased with the results . Thanks Action and your team for doing it right the 1st time.”

-John M., Google Review


We’re Ready to Help!

*Indicates Required Field
Front Page CTA