What Are the Causes of Blown Fuses on Heat Pumps?

Scott Cornell

Heat pumps are a clean, safe and efficient source of heat for residential applications. Unlike other heating systems, they don't generate heat but rather transfer it from one place to another within a home. Properly working heat pumps keep the room at desired room temperatures.

However, one of the most common causes of heat pump system failure is tripped circuit breakers or blown fuses. There are a number of reasons behind blown fuses on heat pumps.


Overvoltage can be a factor in blown fuses. This condition can be either chronic with continuously high voltages, sporadic with high resistive heating demands or intermittent with temporary spikes and surges. When the fuse blows, it's usually easy to determine if it's the result of chronic overvoltage, but sporadic and intermittent overvoltages can often go undetected because they are only temporary.

Electrical Shorts

When troubleshooting heat pumps, the first thing to look for is whether or not the pump is receiving power. For instance, you will need to reset a fuse once it's blown. However, if fuses continue to blow and trip the circuit breaker, that could mean there is a short in the electrical system wiring providing power to the furnace. This could be a complicated do-it-yourself fix and may require assistance from an electrical contractor.

Low Airflow

Reduced airflow can lead to blown fuses in a heat pump system. Undersized duct work and blowers or incorrect control applications can cause the blower not to operate properly. This could lead to overvoltages that could blow the fuse. Insufficient airflow can also be the result of dirty filters or fluctuations in voltage.

Cold Weather

Most heat pumps feature auxiliary heating elements to provide excess heat when the weather becomes colder and heat pump efficiency drops too low. These elements typically turn on at low temperatures and may be drawing too much power. If the weather is very cold, the system can draw enough power to trip the circuit breaker. This can be fixed by resetting the breaker for the pump.