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Serving Maryland, Virginia,
and Washington, D.C.

Serving Maryland and Washington, D.C.

Serving Fairfax and Loudoun
Counties and the surrounding area

24 Hour Emergency Services, 7 Days a Week

Home of Mr. Heat Pump

B&B Air Conditioning & Heating Service Blog

AC Short-Cycling: What It Is, Why It’s Bad


An air conditioning system can run into several different types of malfunctions over its service life. One of the more common is called short-cycling, which is both a symptom and an underlying problem. If an AC begins to turn on and off rapidly over a short period of time (four times or more during an hour), then it’s short-cycling. If you notice this occurring with your air conditioner, please don’t shrug it off or hope it gets better. This is a major malfunction that can warn of several significant underlying problems that require professional air conditioning service in Damascus, MD.

The Specifics of Short-Cycling

An air conditioner runs in cooling cycles where the compressor turns on. The average cooling cycle lasts for 15 minutes or more, enough time for the AC to evenly distribute cooling around the house. When the thermostat registers that the air conditioner has reached the target temperature, it signals the AC to cycle down. The AC will remain off until the thermostat detects that it needs to turn back on.

If something interrupts the cooling cycle and stops it after less than 10 minutes, only for the AC to turn back on a short time later, it is short-cycling. The AC will turn on and off rapidly, far more often than it’s designed to.

Why Short-Cycling Is Trouble

Short-cycling is a problem for several reasons.

  • The constant start-stop places a large amount of strain on the system. This will increase the number of repairs the AC needs and will lead to an early breakdown and replacement.
  • Because the air conditioning system draws on the most power during start-up, continually restarting will place a larger drain on power and drive up electrical bills.
  • Short-cycles will not allow an AC enough time to evenly distribute cooling around the rooms, leading to uneven cooling and hot spots.

What Causes Short-Cycling

Many different malfunctions can lead to an AC short-cycling, which is one of the reasons you’ll need professionals to diagnose the problem and make an accurate repair. Here are some of the most common causes of short-cycling:

  • Refrigerant leaks
  • Miscalibrated thermostat
  • Clogged air filter
  • Dirty condenser coil
  • Frozen evaporator coil
  • Air leaks in the ductwork
  • Oversized air conditioner
  • Air conditioner that’s too old

Some of these troubles are easy to correct: we recommend you change a dirty filter on a short-cycling AC to see if this remedies the issue. On the other hand, an aging AC or one that was incorrectly sized when installed requires replacing the entire air conditioning system. In most cases, you’ll need HVAC professionals to do a targeted repair to get the air conditioner back to normal cycling. 

The Opposite Problem

Although no one in the HVAC industry uses the term “long-cycling,” an air conditioner that won’t cycle down is another common problem—one that also needs a response from professionals. If you hear the AC running all the time, even if it isn’t providing cooling, you’ll want that fixed before the AC wears down and leaves you with a steep electrical bill!

When you need AC help, call on B&B Air Conditioning & Heating Service: We are always there when you need us.

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