Answered: What Temperature Should Your Home Air Conditioner Blow?

Ever wonder how cold your air conditioner should blow? When you turn on the air, you expect it to blow out ice cold. Sometimes it just doesn’t feel like it’s as cool as it should be.

Of course, having an air conditioner blow warmer than it should isn’t just an annoyance. It also wastes time and energy. Just like a car that gets bad gas mileage, an air conditioner that’s not cooling as much as it should means money out of your pocket.

So how cool should the air coming out of the vents be? As a general rule of thumb for home air conditioners, the air should be about 15-20 degrees cooler than the air taken in.

In other words, if the air temperature in your house is 78 degrees, then you would expect the air coming out of the vents to be between 58 and 63 degrees. Don’t worry if the air isn’t exactly in this range, but it should be close. Any cooling differential of less than 10-12 degrees could indicate a problem.

Air conditioning unit outside

How to Check the Air Temperature Accurately

If you want to check to make sure your air conditioner is blowing cold enough, it’s very simple to check. The only tool you will need is a infrared thermometer. While this sounds like an expensive device, you can pick them up for about $20 on Amazon.

With your thermometer, you first want to take the temperature at the
at the air intake. This is where the air is pulled into your air conditioning system to be cooled. You don’t want to simply take the temperature at the thermostat or elsewhere in the house because it is possible that the temp with vary from place to place in the house and give an inaccurate reading to how much the air is actually being cooled.

Next, you want to take the temperature of the air coming out of the vents. Simply point your thermometer into the vents to take the reading. If you have central air conditioning with ducts that run through the attic then you will likely notice a variance in temperature from vents that are close to the indoor air conditioning unit (sometimes located in a closet or sometimes in the attic as well) and those that are farther away.

As the cooled air is blown through the ducts, the attic air will warm it. Therefore it’s not unusual to see the temperatures in some closer vents read several degrees lower than vents that are across the house.

To get the best read on the temperature differential, you’ll want to take the reading at the vents closest to the air intake. This is because this air has the least amount of distance to move, so it’s least impacted by temperature differences.

Remember, you should be seeing a reading of 15-20 degrees cooler between the intake air and the conditioned air coming out of the closest vents.

What If You Have Big Differences in the Vent Temperatures?

If during your readings you find that there are major differences in the air coming out of the vents (differences of 5-10 degrees or more), there are any number of issues it could be. Most likely, however, it has to do with your ducting that funnels the air from the air conditioner to the vent. Many times the insulation on the ducts can be ripped or torn or simply too thin. This allows the heat from the attic to warm the air inside the duct.

What If My Air Conditioner Isn’t Cooling Enough?

If during your tests you find that you aren’t meeting the 15-20 degree differential, then it’s best to have a professional come check your system. The number of potential issues can range from low refrigerant to not enough insulation to dirty coils that cause inefficient cooling. The good news is that most experienced HVAC (heating, ventilation, air conditioning) technicians can pinpoint the problem quickly and get you back to blowing cold air.


  1. So, you’re saying if it’s 100° here in Texas, then all i can expect is 85 in my house. Those differentials are the oldest lamest stats that have no basis in fact.

    Let’s see, it’s 100 outside and you want to go to the grocery, or movie, or restaurant, wear shorts and t shirts, it’s gonna be 80-85 in those establishments! Wait! It’s sometimes freezing in those places, how can that be? They’re not abiding with the 20 degree diff!

    People, if you believe what they’re telling you, just run.

    If your vents are higher than 43-44, your house will never keep you cool when summer comes. Plain math. And common sense

    • No, if it’s 85 in your house, then the vents should blow around 60 degrees. It’s not dependent on the outside temperature, apart from what warms the house, making the air conditioner work harder. Poor insulation, thin windows, etc. can lead to more heating of the home from outside, making it harder for the A/C to keep up.


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