How to Tell if Your AC is Working Properly

If you’ve ever thought to yourself, “How do I know if my air conditioner is working the way it should?” you’re not the only one. The good news is there is a simple test you can do yourself to measure whether or not your AC is cooling like it’s supposed to. All you need is a probe-style thermometer and a little information. We’ll explain each step in this article and show you the steps in this video we made.

During the longest, hottest days of the year your air conditioner is under the most stress and it’s helpful to check in with your AC unit to make sure it’s working properly. If you know what to look for, your system will warn you before it breaks down. The issue is most homeowners don’t know those things to look for. Measuring the temperature split of your unit is a technique trained professionals will use as an indication of potential issues your air conditioner may be experiencing.

The temperature difference between the return air temp and supply air temp is known as the temperature split or Delta T. How you determine the difference is as easy as using a thermometer to check the temperature of the air. If the temps are too high or too low on either end, there is likely an issue.

STEP 1 - MAKE SURE YOUR AC IS RUNNING

In order to get an accurate read, your air conditioner needs to have been running for at least 15 minutes. Go to your thermostat and bump the temperature down about 10 degrees lower than the current temperature reading on the display.

STEP 2 - IDENTIFY THE RETURN & SUPPLY DUCT

Next, you’ll need to go to the furnace to look for the return and supply air. If you have a filter at your furnace, finding these can be easy. The return air will be before the filter and the supply air will be after the filter, where your system turns to silver sheet metal.

Once you identify each, you’ll need an access hole that’s large enough to insert the thermometer. If your system has already been serviced before, you may find that these holes already exist. If not, you may have to drill or punch out a small hole.

ac working properly - identify return and supply duct

STEP 3 - MEASURE & RECORD AIR TEMPERATURES

Next, insert the thermometer into the return. Wait for the thermometer to get a reading and then write down that temperature. Repeat this step on the supply side.

ac working properly - measure and record air temperatures

STEP 4 - DO SOME SIMPLE MATH

Finally, you’ll subtract the supply temp from the return temp. This number is your Delta T, or your temperature split. What you’re looking for is a temperature range between 18 and 22 degrees.

What Does It Mean?

If your temperature is either higher or lower than this range, it means that your system is not able to remove the heat from the home the way the manufacturer designed it to. You could be experiencing any number of issues with your system from dirty coils to low refrigerant.

If your temperature split is in that 18 to 22 degree range but you’re still experiencing comfort issues around the house, you may have a more fundamental air flow issue.

If you ever have an issue with how well your air conditioner cools your home, you may want an HVAC technician to come and diagnose your problem. There are more tools, more diagnosis tests to run and many more parts that should be checked to get an accurate sense for what’s happening.

There are some simple things you can do today to make sure your air conditioner does the best it can to keep your home comfortable. Check out these 8 Air Conditioner Maintenance Tips You Can Do Yourself.

Please share this with a friend if you found this helpful. We hope you stay cool this summer! And we’re always here if you need help.

Other helpful articles:

🛠️ DIY videos from Any Hour Services
🎙️ Listen to Our Podcast - In the House
🎥 Watch our VLOG - Along For The Ride

Jun 23rd 2021

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