Here's a Super Easy Way to Test Your A/C's Efficiency - Parker & Sons Skip to content

Here's a Super Easy Way to Test Your A/C's Efficiency


As the heat continues to blaze on here in The Valley, there’s just about nothing more important than an efficient A/C system. Does yours pass the test? Find out now:

We’re about to give you a straightforward DIY way to test whether your A/C is efficient enough or whether something is wrong (something that could eventually lead to a system breakdown later, and that is costing you money now!). You don’t have to be a technician to perform the test. It’s so easy that anyone can do it!

Step 1: Make sure your A/C has been running for at least 15 minutes

Only do this test if your A/C has been on for a while. Otherwise, the results could be inaccurate. Give your A/C a chance to “warm-up” (AKA cool down) before starting.

Step 2: Take the temperature from the supply vent

Next, you’ll want to take the temperature of the air blowing into your home. If you don’t have a thermometer that takes ambient temperature, you can purchase a digital thermometer in stores or online for $5-$10. Hold the thermometer in front of a vent where the air is blowing into your home (that’s the supply vent!), which is usually on the ceiling or high up on the wall. Make sure to hold the thermometer, or place it inside the vent, for at least 5 minutes. This ensures an accurate reading!

Step 3: Take the temperature of the return vent

Now, take the air temperature in front of a vent where the air is being sucked in. (This is the return vent, where the air is taken in so that it can be passed over the cold coils of the evaporator and become cold again!) These vents are usually located on the ceiling, and can often be found in an area near your thermostat. You will want to take the air temperature right in front of this vent and, again, hold the thermometer in place or put it inside the vent for at least 5 minutes.

Step 4: Is your A/C efficient?

As you’ve probably guessed by now, the way to measure A/C efficiency is by taking the difference between the supply temperature and the return temperature. More specifically, the supply temperature should be cooler than the return temperature, or else you’ve got an A/C problem! But, if the return temperature minus the supply temperature is at least a 15-degree difference, that indicates an efficient A/C system! It means that the air delivered into your home is way cooler than the air going back into the system, which is precisely what you want.

If you’re not entirely confident in these results, or if you KNOW your A/C isn’t cooling your Phoenix home sufficiently, give Parker & Sons a call! We can run several more tests to quickly and correctly diagnose the issue. Schedule an appointment with us online, or call 602-273-7247!

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