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Should AC Fan Be On Auto or On?

Do you like to have control or are you more of a “go with the flow” type? If you’re the kind of person that likes to be in control of your air conditioning, the Climate Control option in your car may surprise you. 

Most of us get in our hot cars and desire an instant cool down so we turn the temperature to Low and turn the fan to high, hoping that the higher the level, the faster the car will cool off. 

If you prefer to control the air conditioning yourself, you may not even be aware of the Auto Climate Control feature in your car. If you prefer to control the air conditioning yourself, you may be surprised how well the Auto Climate Control function really works, once you decide to relinquish that power. 

So, what’s better? Should the AC fan be on auto or simply, on?Why AC Fan Should Be on Auto

What Is the AC Fan?

Vehicles today have one multi-speed fan that blows air through the ducts and vents based on the driver’s desired level. The speeds are controlled by a resistor or a computer control module activated by the blower fan switch. 

When the AC fan is not working it’s usually caused by some sort of fault in the blower motor or resistor. The blower motor resistor heats up as it powers the fan and over time can burn out causing some speeds of the fan to stop working. The fan could be stuck on one speed, only work on the highest setting, or not work at all. 

If the blower motor is not the cause of the trouble, you may need to change your cabin air filter. Cabin air filters ensure no contaminants or particulates enter the vehicle, however, over time these filters can become clogged and prevent the flow of air, impeding your air conditioner’s ability to blow properly.

Climate Control Systems

Home air conditioning controls seem a little more simplistic compared to your traveling air conditioner. At home, there’s one constant blower speed that produces cool air until it reaches the thermostat’s setting. However, your car has two ways of adjusting the temperature: by varying the blower speed and mixing both hot and cold air. 

Cars that have an automatic climate control system can actually take the guess work out of finding that perfect temperature and blower speed. Here’s how it works:

  1. Press the auto button near your air conditioning controls.
  2. Select your desired temperature. In many modern vehicles, both the driver and the passenger have the ability to set their own desired temperatures.
  3. Once the temperature is set and the system is on the auto setting, the car’s air conditioning automatically adjusts between heating and cooling to maintain the desired temperature in the car. 

Don’t worry, if giving up the AC control sends you into a panic, you can always turn the auto function off by adjusting the controls at any time. 

Why Use the Auto Function?

Besides producing cooler air faster over the usual blast of hot air, perhaps the best reason to use the auto climate control function is to save on fuel costs. 

Your vehicle’s battery maintains its charge thanks to the alternator that receives power from the engine. As you know, the engine requires fuel for power. The more pressure you place on your air conditioner, the more power your battery demands, and thus the engine works harder to keep the alternator charged and requiring more fuel. 

For example, when you get in your car and turn the air conditioner to the coldest setting and the fan on high, you’re demanding a lot from the compressor, the battery, and the engine. Once the car finally cools to your desired temperature, you turn the fan down, and may even turn the temperature up a few degrees because now, you’re cold. 

However, if you use the auto setting, the temperature will get down to the desired number as quickly as possible and maintain that temperature. By selecting the Auto feature, the system knows exactly how to reach the desired temperature using the correct blower speed and a more efficient use of the battery, alternator, and ultimately the engine.

Being in control when you drive is a must, but that doesn’t mean you have to control everything. Try running your air conditioner on auto for a month or so and see for yourself how quickly your car cools down and how much more efficiently your car consumes fuel. You might just be surprised at the results!