How Cold Should My AC Be?

On one of these milder days, it’s a good time to go ahead and cycle-on your AC. You don’t want to be in May realizing that you need a service call, only to be told, “We’re backed up. It'll be Wednesday when we can get there…” UGH!

Here are some easy maintenance tasks that are due with your AC:

  1. Grab your hose, and spray the outside of your exterior unit. Use your thumb or a spray nozzle to create a strong force of water to blast the dirt and crud out from between all of those 1000’s of tiny fins. Easy does it; don’t soak the electrical connections.

  2. Change your filter. (The higher the MERV rating the better). Use a sharpie to date the filter. Put an alarm on your phone’s calendar for October, to change the filter again. (I buy my filters online, in bulk).

  3. Replace the batteries in your thermostat (if needed), AND in your smoke/fire alarms. (I have to change them in my RING doorbell too).

  4. Trim any bushes or landscaping that interferes with the airflow around the exterior AC unit. You need a free flow of air circulating through those tiny fins.

  5. Relocate any curtains or furniture that blocks the airflow of SUPPLY and RETURN air vents inside your home.

Now that we’ve got the easy maintenance tasks handled… let’s answer our question.

 “How cold should the air be that comes out of my vents?” 

Well, it’s complicated… but I’ll give you some general information that hopefully won’t get me in trouble with my HVAC buds. Remember: I am not a licensed HVAC tech. My comments are born from 20 years experience getting homes comfortable for homeowners..

  1. Residential A/C equipment technology is designed to remove heat. About 18-22 degrees is the average temperature “drop” (or ‘Delta T’) that occurs inside the AC equipment in your attic or crawlspace.

  1. So, let’s say the temperature of the airflow moving into your RETURN air vents is 76 degrees. That airflow is blown through the heat exchanger in your attic or crawlspace where the cold refrigerant is moving through the “coils” (imagine your car radiator). Heat is removed from the 76 degree airflow, and the resulting temperature of the airflow after it’s passed through the coils should be 18-22 degrees cooler.

  1. Twenty degrees deducted from 76 degrees is 56 degrees. So the airflow coming from your SUPPLY vents, with the AC running, would be approximately 56 degrees in this example.

Are there exceptions and variables… Absolutely.

  1. Are your ducts in the attic? A vented attic in Atlanta’s summer season can reach temperatures of 140 degrees! Over & over again I’ve seen airflow temperatures at the AC vents negatively impacted by the inferno-like conditions in a vented attic. Leaks in your return air-ducts suck-in that super-heated air, increasing the air temp that your AC has to drop!

  1. If your AC system isn’t properly charged (too high or too low pressure), it will negatively affect the performance of your system, and the air temp will not be as cold as it could be.

  1. Vents that are closer to the air handler may have colder airflow temps than those vents that are further away. This is especially true for ducts located & suspended in a vented attic.

  1. Let the system run about 10 minutes before testing. 

Certainly there is much more to this subject than I’ve put in this short article. My intent is to keep this at a 6th-grade comprehension level, because that’s where I like my communication!

Homeowners ask me this question throughout the summer season. I hear it often.

Is there a quicker answer or rule of thumb?

I used to simply give a small range, like this, “A good range that I’ve been told by the pros, is from the high 40s to the mid 50s”. And I’ve found this to be true many thousands of times in my own simple tests.

For systems mounted in the basement or crawlspace, my brief answer was fine. But for systems mounted in vented attics, it was rarely true in the hot summer months! So… I try to share both answers when my homeowner sees the higher temperature readings from an upstairs level where the AC is located in the attic.

Here’s Hope...

I hope this helps! Struggling with an uncomfortably warm home, or rooms? We Can Fix That! We’ve Got The Answer!

Call the Bird Family, at Bird Family Insulation. We’re here to help. 404-538-9168.

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