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Short Cycling – Why Air Conditioner is Turning On and Off Rapidly

Cycle Arrows

What is Short Cycling

Many customers experience a problem where they notice their unit is frequently turning on and off rapidly, this problem in the HVAC world is known as short cycling. We can start off by saying that you should be concerned because it is bad for the air conditioner, as it can cause a breakdown and increase electric bills. There are a few reasons why this happens; we’ll cover them below.

Why Short Cycling Happens

Your unit is short cycling due to overheating, electrical problems, or the unit may be too big.

Over Heating

Your air conditioner may be short cycling because it is repeatedly starting up then overheating (and shutting down) due to a bad compressor, dirty filters, dirty coils, low refrigerant, or frozen coils. An overcharged system will cause liquid Freon to get into your compressor and cause it to malfunction. A malfunctioning compressor will overheat. Dirty filters will prevent adequate airflow and cause motors to overheat. Dirty coils, low refrigerant, and a frozen coil will prevent the system from absorbing heat which will also cause motors to work harder than necessary and overheat. Overheating may be your short cycling problem.

Electrical Problems

Your system can be experiencing electrical problems from the thermostat, electrical connections, circuit boards, and run capacitor. The thermostat is the brain of the air conditioner, a bad thermostat can be causing your system to cycle on and off rapidly. Electrical connections send signals between the thermostat, circuit boards, and relays; bad electrical connections can lose signal, causing your unit to shut off early and short cycle. Circuit boards may also have gone bad or there are bad connections to them. Start capacitors help the unit start and a bad run capacitor will prevent the unit from running, so the unit may be starting up but if there is a bad run capacitor then it won’t continue to run. Short cycling can occur from the thermostat, electrical connections, circuit boards, and run capacitors.


An oversized air conditioner will cool your home quickly but not reduce humidity and will short cycle. The unit cooling the home quickly causes it to turn on and off rapidly (short cycle) since cooling is achieved quickly. Even though your home may be cooled down, the rapid on and off will cause problems for your air conditioners components. Parts will begin to breakdown. Also, an oversized unit does not do a good job of humidity removal; extra moisture in the air will cause pockets of heat in the home since moisture absorbs heat. Your air conditioner may be too big.

Increased Electric Bills

Short cycling increases electric bills. The immediate starting and stopping of the air conditioner cause quick and sudden burst of energy usage. At the same time, the unit is struggling and working as hard as possible. The short burst of your air conditioner running at max power is going to cause your electricity bills to go up. How much electricity is being used depends on how much the thermostat is being satisfied, the less satisfied the more it will try to run.


You can prevent most air conditioning problems with routine maintenance checks. The technician will be able to tell you what you can do to take care of your unit once he does the check.

Short Cycling Solution

Finding a solution to this problem is not a DIY kind of project. If your in the Phoenix area, contact us for service.

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