Why is my furnace blower constantly running?

If your fan limit switch is set to AUTO but the fan continues to run without ever stopping, you’ll need to call a professional. Two problems that could cause your fan to run without stopping include: A bad fan limit switch that needs to be replaced. Bad thermostat wiring.

Should blower run constantly?





Better Indoor Air Quality
Whenever the fan is on, air is going through the furnace filter. Leave it on continuously and you’re likely to see less dust around. It’s also important to have a good filter. The many types of HVAC filters can help reduce allergies, VOCs, as well as bacteria and viruses.

Why is my fan running when my thermostat is off?

If the fan is the only thing running when the AC unit isn’t, there may be a faulty relay switch prohibiting the settings on the thermostat from being communicated to the fan. Another cause could be a wiring issue or a short circuit preventing the system from recognizing the on and off signals.

Why is my heater not turning off?

If your heater won’t turn off, the first thing you do is check the thermostat. The thermostat controls how the heating system runs. It detects the indoor temperature and signals the furnace to start or stop. So, if the thermostat malfunctions, it can signal the unit to run continuously.

Why is my furnace not shutting off?

If your furnace won’t shut off, you likely have one of the following issues: Thermostat issue. Dirty air filter. Faulty blower.

Is it better to leave furnace fan on or AUTO?





“auto” is the best setting for your furnace fan in the winter. It will aid in saving energy and money while also working to keep your home at an optimal temperature. However, for summer, “on” is the best setting for your furnace fan.

How long can a furnace run continuously?

Typically, the furnace should run, on average, 10-15 minutes during each cycle on a typical heating cycle. If your furnace continues to close off, check your air vents to check whether any of them are shut or obstructed in any capacity.

Should fan be on AUTO or on?

Keeping your fan on AUTO is the most energy-efficient option. The fan only runs when the system is on and not continuously. There is better dehumidification in your home during the summer months. When your fan is set to AUTO, moisture from cold cooling coils can drip and be drained outside.

Is it normal for heat to run constantly?

Understanding Ideal Heat Pump Performance
When temperatures dip below 40 degrees, the heat pump is designed to run almost constantly to keep your home comfortable. So, if the weather outside is particularly cold, and your system is running constantly, don’t worry. It may mean it’s working as it’s supposed to.

Why will a blower run on the on position and not on auto?



The fan will run and blow warm air but only in FAN or FAN ON mode – delivering heat – but NOT in AUTO mode. This is a bad temperature sensor in the unit; replace the fan limit controller.

Where is the blower motor reset button?

Locate the reset button on the furnace and press it to reset the furnace. It is usually located inside the blower compartment on the side of the blower motor. Be cautious as the housing may be hot. If the button is popped up, press it down.

How do I reset my thermostat?

Here are the step-by-step reset instructions:

  1. Turn your thermostat off by switching it to the off position.
  2. Find the breaker that powers your HVAC system and turn it off.
  3. Wait 30 seconds and turn the breaker back on.
  4. Turn your thermostat back on.


Should you run your furnace fan 24 7?

Less frequent starts and stops of the fan can reduce the stress from startup, and potentially help extend it’s lifespan. Leaving the fan on 24/7 ensures cleaner air, as the air is pulled through the filtration or UV light system. This can be better for people with allergies.

How long can a fan run continuously?

On average, though, it’s safe to leave your ceiling fan running for eight consecutive hours at a time. That doesn’t mean you should panic if you ran out the door for work and forgot to turn your fan off, but you will want to give the fan’s motor a break as soon as you get back home.