Should Ac Fan Be on Auto or On

Should Ac Fan Be on Auto or On?

What is auto mode in AC?

Auto mode on the AC simply means that the fan on the air conditioner turns on automatically while the air conditioning is running. Once the room gets to temperature,  it then shuts off.

The ON position for the fan means that the fan will continuously run even when the air conditioner is not running.

Should Ac Fan Be on Auto or On?

Using the AC fan on Auto is considered the energy and money saving mode.

Here are a few reasons why:

Running fan on air conditioner continuously


  1. Increase Energy Bill
  2. Use More Filters
  3. Increase Relative Humidity
  4. Cool Air Leakage
  5. Increase Repairs

What is auto mode in AC1.  Increase the electricity bill.

By constantly running the fan you will bump up your energy bill.

2. Increased Filter Replacements

Continuously running the fan will called you to go through more filters because of the extra use.

3.  Increases the level of relative humidity.

When the AC is off, the dehumidifying function of the air conditioner is off to.
The moisture that would drain out while the fan is off doesn’t get a chance and is recirculated around the house with the fan on.
 Which means that the air conditioner has to work extra hard when it kicks back on to combat the extra humidity in the air.
That means a higher energy bill and more chances of service calls.

4.  Cool air leakage.

Air ducts or not foolproof and do have a fair amount of leaks. Keeping the fan running while the air conditioner is off can cause the cool air to leak out faster.

5. General repairs.

The fan motor running 24/7 will shorten the life of the motor. 

There are some advantages to leaving the fan on all the time.

  1.  The fan will help keep the temperature even throughout the house when the AC has turned off.
  2.   The HVAC central heat and air unit is actually a very efficient whole house air purifier when there is UV ionizers placed in the ductwork.

These in duct air purifiers require the air to move through the house regularly  work right.

Running AC fan only?

Having the fan on can help even out the temperature throughout the house by redistributing the air.

But, the AC fan doesn’t really cool down the house on its own. It is primarily used to circulate air through the ductwork and doesn’t have too much of a cooling fan effect otherwise.

The main reason you might want to keep the fan on the air conditioner running continuously is when you are using induct air purification which needs the fan to circulate the clean Air throughout the house.

Running AC fan only

Published by

Dennis Reed

Dennis Reed Owner and Author @