Reasons Your Furnace or Heat Pump Keeps Blowing Its Fuse

Wind chill, freezing temperatures, ice accumulation and heavy snow — the winter season brings a variety of adverse weather extremes that increase your need for indoor heating. During cold winter weather, the last thing you want is to encounter technical problems with your heating system–be it a furnace or a heat pump–particularly a blown fuse. The fuse is designed to protect the system from a potential short or overload, so when it blows, a host of complications can arise.

In this article, a heater and AC repair specialist discusses the common reasons your furnace or heat pump keeps blowing its fuse and how to prevent or resolve them.

Dirt and dust. Over time, dirt, dust, grime and other contaminants can accumulate and make their way from the air filter into the blower motor, the component responsible for moving heated air through vents. This can cause the motor to overheat and eventually burn out, resulting in the high limit, a built-in safety mechanism that controls the opening and closing of the heater, to malfunction. Moreover, when the high limit becomes caked with soot and debris, the connection will break and the limit will fail.

Overheating or a high limit switch that trips often are warning signs that your heating system hasn’t been serviced in a long time. To prevent these situations from occurring, be diligent in maintaining your furnace or heat pump, including all of its electrical components, and schedule a cleaning and tune-up service at least once a year. Also, don’t forget to replace your air filter every three months. Thicker filters have more room to collect dirt and dust, so they don’t have to be replaced as often, say furnace and AC repair experts.

Loose wires. Over the years, internal wires or electrical connections can loosen due to the natural vibrations of a running furnace or heat pump. If a wire becomes loose or disconnected, it can cause a short, causing the fuse protecting the unit to blow, or worse, become hot enough to start a fire or create serious shock hazards. Since locating, fixing and replacing loose wiring is normally a difficult task to accomplish on your own, it’s a smart move to ask for the assistance of an HVAC professional. Additionally, regular inspections and safety checks will ensure all your heating system’s wires are tight and secure.

Faulty parts. Parts of your furnace or heat pump may start to deteriorate or break down after years of use. A clear indication that you’re dealing with worn-out or faulty parts is loud, unusual noises. 

• A faulty run capacitor. When a capacitor fails, the motor can exhibit a variety of electrical issues, such as failing to kick-start the system, overheating and vibrating. When a faulty capacitor causes the heating system to become too hot internally, it can trip a safety switch, shutting down the unit temporarily. In most cases, a faulty capacitor will need to be replaced. Leave it in the hands of heating and AC replacement experts to find the correct replacement unit and handle removing the old one safely.

• A faulty transformer. The transformer is responsible for increasing or decreasing the voltage to run the ignition, timers and controls. When the efficiency of this component is reduced, voltage surges may occur, causing the circuit breaker to trip more frequently. Voltage surges can fry various parts of your furnace system, so be sure to call in a professional technician to resolve the problem.

• A faulty valve. If you have a gas-fueled furnace with a fuse that keeps blowing, inspect the safety valve on the equipment. It should be able to open and close when needed. If the valve is clogged, it may be forcing too much out or keeping too much heat inside the unit. In many cases, this can cause the furnace to overheat, potentially igniting a fire. While it’s perfectly okay to fit a new valve on your own, it can be extremely dangerous if you don’t get it right. You need someone who’s knowledgeable and has access to the right set of tools to carry out the task without a hitch.

Incorrect fuse size. If the furnace fuse is too small and can’t handle the wattage, this can be a cause of the fuse blowing. A certified furnace and AC replacement technician can determine the problem and replace your existing fuse with a new one that has sufficient capacity to handle the electrical demands of your heating system.

Malfunctioning thermostat wire. If the thermostat wire grazes the metal frame of an electric-powered furnace, it can lead to a blown fuse. This is because when the wire touches the metal frame, it can deliver a higher voltage than the wire is designed to handle. Consequently, this will blow the fuse on the control board, preventing the draft inducer from starting, which then keeps the rest of the furnace from functioning properly.

Low airflow. A case of reduced airflow can spring from different circumstances, such as a limited number of return air vents, misconfigured duct runs and holes in the air ducts. However, in many residential applications, undersized ductwork and incorrect control applications usually cause the blower not to operate properly. There’s a real likelihood that one of these scenarios will lead to an overvoltage incident that will blow out the fuse in your home. Insufficient airflow can also be the result of dirty air filters, so make sure to include these items on your maintenance checklist.

Water leaks. It’s not unusual for a leak to occur in your furnace or heat pump. While moisture or water droplets dripping from a humidifying device attached to the equipment may seem inconsequential, this isn’t an excuse to neglect the issue. If not taken care of right away by a furnace and AC maintenance specialist, water leaks can inflict damage on your furnace or heat pump. Calling in a technician to patch up any leaks will help prevent further, more expensive damage to your heating system.

Cold weather. In the winter months, furnaces or heat pumps aren’t spared from the challenges of bitterly cold weather. Many modern-day heat pumps feature auxiliary heating elements that provide additional heat when outdoor temperatures start to drop too low and the efficiency of the equipment decreases. These elements are expected to switch on when extremely low temperatures are detected. However, one downside is that they may draw too much power. If the weather is freezing cold, the heating system can guzzle enough power to trip the circuit breaker. The good thing is, this can be fixed by simply recalibrating the breaker for the pump. If this step doesn’t resolve the issue, it’s time to bring in a technician.

Contact Us for All Your Air Conditioning and Heating Needs

If you need a reliable furnace and AC maintenance technician to assess your HVAC equipment, look no further than Cool Zone Air Conditioning & Heating. From tune-ups and safety checks to installations, replacements and maintenance services, our skilled, experienced team has got you covered. Our goal is to build long-lasting relationships with our customers by providing superior workmanship and personable customer service. Schedule an appointment with us today by calling (623) 253-1018, or complete our convenient online form and we’ll get back to you shortly.