Short cycling is one of the reasons why an air conditioner may not cool as effectively as it should. When this happens, it can take a toll on your central air conditioning system's longevity and prevent your home from staying cool and comfortable during warm weather. Learn about the causes behind short cycling, how it affects your air conditioner and ways you can prevent it from happening.
What Short Cycling Does to Your Air Conditioner
It's normal for an air conditioner's compressor to cycle on and off, depending on cooling demands. This means the compressor can stay on for hours or for just a few minutes. What isn't normal, however, is the compressor constantly cycling on and off for minutes at a time.
This constant cycling can cause excess wear and tear on the compressor, eventually wearing it out prematurely. It can also add stress to other central A/C system components and prevent your system from cooling your home effectively.
Common Causes of Short Cycling
Any number of air conditioning issues can cause short cycling, but the following are the most commonly dealt with by HVAC contractors and homeowners alike:
- Lack of refrigerant – Low refrigerant levels can easily damage the compressor and cause the evaporator coil to freeze over. To prevent this, most central A/C systems feature low pressure controls that shut the compressor down when refrigerant levels reach critical levels. This can cause the compressor to short cycle as it shuts down and attempts to start up again.
- Oversized A/C system – A system that's much larger than the space it's cooling will cool that space pretty quickly. This causes the unit to constantly shut down and restart as it attempts to maintain a set temperature. Short cycling is one of the reasons why it's important to properly match a new central A/C system's cooling capacity to the rooms it'll soon cool.
- Poor thermostat location – If the thermostat is mounted too close to the A/C system's return air supply vent, chances are it'll mistake the blast of cold air as a sign that it's fulfilled its cooling duty and shut down. Unfortunately, the surrounding warm air will simply kick the A/C back into operation. This can happen repeatedly, causing those short cycling issues.
- A faulty low pressure control switch can also cause short cycling behavior.
Solving the Problem
After figuring out the problem, it's time for a solution that can help restore overall home comfort.
- Short cycling problems involving low refrigerant levels are often traced back to a leak somewhere within the system. If you suspect your A/C system needs more refrigerant, you should have a qualified technician recharge the unit and check it for any leaks.
- For short cycling problems caused by oversized A/C systems, you should reevaluate your cooling needs and, if possible, select a new system that's the proper size for your home. This can be done with the help of a Manual J load calculation and Manual S equipment selection process.
- Relocating the thermostat away from air supply vents and other areas immediately affected by colder air flow may also help. Your technician may be able to help with the relocation process and it may even be a good time to upgrade to a programmable thermostat, if you haven't done so already.
- Have your technician carefully inspect your central A/C system's internal components for signs of failure or malfunction. Such an inspection could pinpoint worn, defective or damaged components that could lead to short cycling.
If your compressor is already suffering damage from periods of short cycling, then it should be replaced as soon as possible. A damaged compressor can easily introduce badly handled refrigerant and metal shavings into the refrigerant oil supply, damaging the rest of the system.