Why Is My Air Conditioner Constantly Running?

It’s summertime, and you’ve noticed your AC never stops running.

Should you be concerned?

Here’s the thing: It’s normal for your AC to run continuously during hot summer months.

You see, on extremely hot days—we’re talkin’ high 90s to 100s—your system needs to keep up with the incoming heat. To do that, it will run longer in order to maintain a constant, desired temperature in your home.

However, if your AC is always running but you’re never comfortable, that’s a clear sign of a problem that needs to be fixed.

Here are 4 common causes of an AC that constantly runs and never delivers.

Cause #1: Restricted airflow/low blower speed

Your system requires a certain amount of airflow to cool your home. If airflow is blocked or restricted in any way, your system works harder and runs longer.

Sign of this problem:

  • Cool but weak airflow coming from vents

What to do:

Common culprits of this issue include dirty air filters, leaky or disconnected ducts and closed or blocked air vents. So…

Cause #2: Dirty evaporator and/or condenser coil

If your inside unit’s evaporator coil is dirty it makes it tough for refrigerant (or “Freon”) to absorb heat from your air.

The same goes for dirt buildup on an outside unit’s condenser coils. A dirty condenser can block the release of absorbed heat from the refrigerant.

Basically, both issues will cause your system to run constantly since it’s struggling to remove heat from your home.

Signs of this problem:

  • Air from vents is warm or not cool enough to reach desired temp
  • Dirt is visible on outside unit/inside coils

What to do:

Clean the outside unit yourself. Or have a trusted professional do it as part of a routine maintenance plan. You’ll need an AC pro to clean the inside unit’s coils anyway.

Cause #3: Low Freon/refrigerant

When your system is low on refrigerant, it will struggle to reach the temperature setting, causing it to run constantly.

Signs of this problem:

  • Ice buildup on the refrigerant line and/or the outside unit
  • Bubbling or hissing noise
  • AC is blowing warm air from vents

What to do:

You need a professional to check your system's refrigerant level. If it’s low, make sure they find and fix the leak (since a leak is why you lose refrigerant), and then add more.

Read more on refrigerant leaks.

Cause #4: Undersized air conditioner

An undersized AC is like “The Little Engine That Could” but can't. It will constantly run but the system is simply too small to meet your home’s cooling demands.

Signs of this problem:

Airflow from vents is normal but home never reaches desired temp on hot days

Frozen evaporator coil (cooling coil in the inside unit) due to low pressure inside unit

What to do:

Have a professional air conditioning contractor perform a heat load calculation on your home to know what size (measured in tons) your home needs. If you suspect this is your problem you’ll want to fix it fast to prevent costly repairs with your compressor due to frozen coils and constant wear and tear from your system working too hard.

Have questions or need AC repair?

Coolray serves the Atlanta, GA and Birmingham, AL metro areas and has been providing expert air conditioning repair, service and installation since 1966.

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