A dirty furnace filter is the number one reason we’ve found that furnaces run constantly. … The furnace goes into “cool down” mode and runs the fan constantly. Your furnace might even start blowing cold air if this is the problem. The solution is simple: replace the furnace filter.

Is it normal for heat to run constantly?

While a heat pump that runs continuously can be a sign of a problem, sometimes it means it’s working exactly as it should. When temperatures dip below 40 degrees, the heat pump is designed to run almost constantly to keep your home comfortable.

Why is my heat not shutting off?

One of the most common issues is the thermostat. The wiring, switches, or heating sensors can fail on your unit. … A faulty check valve could be the cause of this type of heating system to fail. If your heating system will not shut down, then you need to call a professional technician for help.