Why is My Central Air Conditioner Turning On and Off Rapidly?

Air conditioning unit outside in front of brick wall

July 13, 2023

Got a central air conditioner that turns on and off every few seconds or minutes?

This is called “short cycling” (because normally the AC has a regular on and off “cycle” that varies with the outside temperature.)

Short cycling wears out the outside unit’s compressor. That’s bad because the compressor is so expensive that, if it breaks, many homeowners usually just replace the entire outside unit.

So, what causes short cycling?

There are 3 common causes for short cycling:

Low refrigerant/Freon
Oversized air conditioner
Poorly located thermostat

We’ll discuss these problems in detail in this article.

Cause 1: Low refrigerant/Freon

Your AC compressor has a device called “low pressure control.” Basically, it can shut off the compressor when you’re low on refrigerant.

And if you’re low on refrigerant, that means you also have a refrigerant leak that needs repairing. If not repaired, you’ll have to keep paying for a contractor to add more, which can get pricy.

See our answers to FAQs about refrigerant/Freon.

Cause 2: Oversized air conditioner

An AC that is too large (oversized) cools your home too quickly, so it shuts down and starts up frequently. This causes several problems, including:

Reduced moisture removal (meaning your home feels too humid)
Higher operation costs
Higher risk of premature breakdowns

If your AC is relatively new, try to get a refund and have a professional installer perform a Manual J Heat Load Calculation to find the size that’s right for you.

Cause 3: Poorly located thermostat

The temperature around the thermostat determines how your AC runs.

So if the thermostat is too close to an air supply vent, it gets a blast of cold air when the AC turns on. This signals to the AC to shut off (because the thermostat now think your whole home is cold).

Then the ambient (surrounding) heat around the thermostat warms it up, causing the AC to turn back on. Then the cold air hits the thermostat, turning the AC back off. This is why the AC is short cycling.

Luckily, this is a relatively simple fix – just find a better location for your thermostat. A professional air conditioning company can help you do find the best spot.

Need AC repair in Atlanta, Nashville or Birmingham, AL?

There are other issues that can cause your central air conditioner to short cycle, but these 3 are some of the most common ones.

Want this problem fixed ASAP? If you live in the Atlanta, Nashville or Birmingham, AL areas, schedule a repair with Coolray.

Coolray has been providing expert heating & air conditioning service since 1966.

Related article: Air Conditioning Troubleshooting