Why does my A/C run constantly?

If your air conditioner seems to be running constantly, here’s a quick troubleshooting guide you can follow to fix the problem or at least find the source of the problem.

Step 1: Check your thermostat settings

If your air conditioner seems to run all the time, it could simply be because you have your thermostat set to “on” rather than “auto”

The “on” setting keeps the fan running even if the air conditioner isn’t actually cooling your home. This help evenly cool your home, but also eats up energy if you leave it running 24/7.

Also, make sure that you don’t have your thermostat set too low. The lower you set the thermostat temperature setting, the longer it will run. And if it’s set too low, especially on hot days, it may never turn off.

Most air conditioners are designed to keep your home around 72 degrees.

Step 2: Check your air filter

Has it been awhile since you changed your air filter? It’s probably dirty, which is the cause of this problem. (In fact, this is a common cause for many air conditioning problems).

A dirty air filter restricts airflow, which cuts down on the amount of cool air your air conditioner can produce, making it run longer.

If you’ve changed the air filter and are still having problems, continue to the next step.

Step 3: Make sure all your vents are open and unblocked

Some homeowners in Kansas City decide to close air conditioning vents in some rooms because they think it saves them money.

Actually…closing vents does just the opposite.


Well, closing vents causes your air conditioner to struggle to cool your home to the desired temperature. So it runs longer and more often. This increases energy use and reduces the lifespan of your AC as a whole.

Open up any closed vents and make sure you don’t have any furniture or drapes blocking any vents as well.

Step 4: Find out if you have a two-stage air conditioner

Two-stage air conditioners are designed to run longer at slower speeds. This is more energy efficient than it turning on and off constantly. (it’s just like how your car gets better gas mileage on the highway than surface streets.)

If you have a two-stage AC and the weather outside is less than 90 degrees, then your AC is probably working, as it should.

Step 5: Check your maintenance records

Air conditioning manufacturers recommend getting your air conditioner tuned up at least annually by an HVAC professional. This not only keeps your warranty valid, but it also keeps problems like this from happening.

There are two main problems that can cause your AC to run constantly that a tune-up can prevent.

Dirty coils
Dirt on the coils of your air conditioning system prevents your AC from cooling your air properly, causing your system to run more as it struggles to reach your thermostat setting.

Incorrect refrigerant charge
The refrigerant in your air conditioning system might be low. (Although that means you likely also have a leak since refrigerant is never “used up”.) Low refrigerant means that the AC can’t get your air very cold, causing the air conditioner to run longer to cool your home.

If you haven’t had maintenance done in awhile and the other steps didn’t solve your problem, dirty coils and the low refrigerant are likely culprits.

Step 6: Get professional help

If your air conditioner is still running constantly, it could be a bunch of other technical problems. The best way to find the problem is to get a professional air conditioning repairman to come out and take a look. Contact us today!

Santa Fe Air serves the air conditioning needs of homeowners in Kansas City and the surrounding areas.