No, Turning Your Home Thermostat Lower Doesn’t Make the Air Colder

Over the years we’ve noticed some confusion among some folks when it comes to cooling off with an air conditioner. And we think we know exactly where it comes from…

Here’s the deal — we’ve seen more than one person be blazing hot in a house and crank the thermostat way down into the 65-degree range to cool things off. The thinking is that if they turn the thermostat lower, then the air coming out of the vents will be colder. So if it’s 75 degrees in a house and you turn the thermostat to 73, then 73-degree air will come out the vents. Turn it down to 65 and the air that comes out is even colder.

That’s not the case at all and can actually damage your air conditioner while also jacking up your electric bills.

The fact is that air conditioning units for homes (we’re talking central air units with adjustable thermostats) don’t blow colder when you turn the thermostat down. They simply operate in an on/off program.

Turning thermostat down

Let’s go back to being warm in your 75-degree house. If you turn the air down to 73, the air conditioner will kick on and start blowing. The air coming out of your vents should be about 15-20 degrees cooler than the ambient air that’s taken in. So in this case, you can expect the air being blown out to be about 60 degrees or so. And with the thermostat set at 73, the unit will run until the ambient air temperature is 73 degrees.

Now let’s say you instead crank the A/C down to 65 degrees. As before, the unit will kick on and the air being blown out of the vents will STILL be around 60 degrees (15-20 degrees cooler than the 75-degree temps in the house. In this case, however, the air conditioner will keep running until it cools the entire house down to 65 degrees.

Depending on how hot it is outside, how well your unit runs, and how much insulation you have, this could take hours — if it ever happens at all. In other words, you could be running your air conditioner for hours on end, costing you a fortune in electricity costs.

Car Thermostats Work Differently… That May Cause Confusion

So why is there so much confusion over this fact? We think a lot of it comes from the air conditioning you find in cars. In automobiles, the air conditioner either has a digital dial (like a home thermostat) or the familiar dial that goes from blue to red.

With these dials, the farther you turn the dial to blue, the colder the air gets. So if you want your car air conditioner to blow as cold as possible, you turn it all the way down. Unlike your home A/C, this actually makes the are blow colder.

Given that, it’s no surprise and completely understandable that some people get confused.

Just remember, you home air conditioner won’t blow colder if you turn the thermostat down. It only turns the air on and off. Cranking down the A/C will only raise your electric bills.


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