HVAC fan

Auto or On: What’s the Best Setting for Your Thermostat?

Your thermostat is capable of more than raising or lowering the temperature of your home. Depending on the model, you can create heating and cooling schedules based on your everyday routines, control the temperature remotely through WiFi, and even receive reports detailing your HVAC’s energy consumption. However, one feature commonly mystifies homeowners: the “on” and “auto” setting. This setting refers to your HVAC system’s indoor blower or fan.

Should you set it to auto or on? Here are some pros and cons of each option.

Setting Your HVAC Unit to “On”

When you choose the “on” setting, you’re telling the system’s fan to continuously blow air. Check out the benefits and disadvantages of this setting to find out if it’s the right choice for your home.


Leaving your HVAC’s fan in the “on” position ensures that indoor air is processed through filtration or UV light systems more often. The presence of dust mites, pet dander, and pollen in your home is significantly reduced resulting in cleaner indoor air. Allergy sufferers rejoice.


The biggest disadvantage of leaving your HVAC in the “on” position is high operational costs. It could cost you an extra $50 per month to run your HVAC’s fan continuously.

Running your HVAC in this mode also increases the wear and tear of its components. You may have to replace the fan’s blower prematurely.

Setting Your HVAC Unit to “Auto”

Using your HVAC’s “auto” setting allows you to give your heating and cooling system a break between cooling or heating cycles. The HVAC fan runs only until the temperature reaches the preset temperature. Here are some reasons why this option may or may not be the one for you.


Giving the HVAC fan a rest in between heating or cooling cycles helps extend the life of its components. It also gives your wallet a break since it’s an energy-efficient option that lowers power consumption.

Setting your fan to “auto” results in a less humid home. When the fan is running non-stop but your AC has completed its cooling cycle, the fan blows humid air into your home. By leaving the fan on “auto,” you’ll reduce the humidity levels.


If you have hot or cold spots in your home, setting your HVAC to “auto” won’t help your cause. Continual airflow helps distribute air evenly throughout your home. The good news is that it isn’t the only solution to the problem of uneven temperatures. A lack of airflow that results in hot or cold spots can be caused by leaking ducts. It’s often best to get a trusted HVAC company to inspect and seal the system’s ductwork.

Best of Both Worlds

Setting your HVAC unit to “on” or “auto” is a matter of personal preference, which is why the manufacturers give people the option. However, most homeowners and HVAC professionals prefer the “auto” setting. This setting strikes a balance between comfort and efficiency. However, if you like the idea of continually cycling air to remove impurities, consider upgrading to a central air system with variable-speed technology. This allows the HVAC unit to operate lower and slower for longer periods. That means no more abrupt on and off cycles, more consistent comfort and lower energy consumption. To learn more, contact Jack Frost Heating & Air Conditioning, LLC at (973) 520-0505.