What It Might Mean When Your Air Conditioning Unit Is Turning On and Off

SAN DIEGO, CALIFORNIA — Chances are you won’t think too much about your heating and cooling system until you notice something wrong with it. One of the problems that we get calls about is the unit turning on, running for a short period of time and turning off again — over and over again.

“When an air conditioning system is rapidly starting and stopping, it’s called short cycling,” says Gabriel Carini, the founder and owner of our San Diego air conditioning and heating company. “It’s a problem because it shortens the overall life of your HVAC system and can drive up your energy costs.”

There are several reasons that can cause a heating and air conditioning system to short cycle, but most of them can be prevented or corrected with a few simple steps.

  • Refrigerant leak or improper refrigerant charge

A short cycling unit may be the symptom of a refrigerant leak somewhere within the AC unit. The simplest fix is to add refrigerant and recharge the air conditioning unit; however, that is only a temporary solution. Instead have an air conditioning repair and service technician find and repair the leak to prevent the refrigerant from leaking out again and causing the system to short cycle.

  • Cooling coil iced up

When the evaporator coil or cooling coil of the unit gets covered in ice or frost, it can cause the unit to malfunction by turning on and off in short bursts. This can typically be fixed by turning off the air conditioning unit and letting the ice melt, then checking the air filters, cleaning or replacing dirty ones.

  • Over-sized unit

When a unit is sized correctly, it is capable of removing the heat as quickly as it comes in to the home or business Ideally, the system should be able to keep up with the incoming heat without gaining on it. An over-sized unit will be able to cool the space too quickly and cycle on and off. Every time the system starts up again, it requires a lot of electricity, decreasing efficiency and increasing the electric bill.

“Another drawback to an over-sized unit is that it may not run long enough to remove water from the air, which can result in humidity problems,” says Carini.

  • Loose or disconnected electrical fitting

Sometimes short cycling is caused by an electrical fitting, control board or control switch that has been damaged, jiggled loose or completely broken. Simply replacing, repairing or reconnecting the fitting will resolve the problem and eliminate the short cycling.

“Most of the causes of a short-cycling unit are issues that would have been inspected and fixed during a routine heating and air conditioning service,” says Carini. “Investing in biannual tune-ups and changing your air filter every month will keep your HVAC system from having this type of problem.”

Biannual tune-ups can be scheduled separately or purchased as part of the routine maintenance agreement. During a tune-up, the technician performs a 22 point inspection of the unit, making adjustments and minor repairs where needed.

As for over-sized units, they can be replaced with a unit that is the proper size. If it needs any expensive repairs or if it is 10 or more years old, homeowners may be better off replacing the unit with a two-stage unit.

“A properly-sized two-stage cooling unit is the ideal option for  homeowners who are replacing their unit anyway,” says Carini, who also specializes in business heating and air conditioning services. “These systems are very efficient and effective, particularly for people in San Diego’s relatively mild climate.”

Two-stage cooling means that the air conditioning unit or heat pump has a compressor with a high setting for extra hot weather and a lower setting for milder weather. The maximum output is rarely needed for San Diego residents since temperatures are typically mild, so the system is running at the lower, more efficient setting.

“These systems are more efficient and less expensive to operate than regular systems, but they also provide more consistent temperatures and more effective humidity control,” says Carini.

With some basic monthly maintenance tasks and twice a year service appointments, you can avoid most short cycling problems. If you need to replace your system, we would be happy to assess your home or business and discuss the options for your situation.

 

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