What happens if my AC is oversized?

What happens if your AC is oversized is several comfort and efficiency problems that make home less comfortable despite cooling quickly. Oversized AC means unit has too much capacity, for example 4-ton for home that needs 2.5-ton, or 3-ton for 1200 sq ft that needs 2-ton. First, short cycling occurs where AC runs only 5 to 10 minutes, cools air quickly to thermostat setpoint, then shuts off, then restarts 10 minutes later, causing frequent on-off that increases wear on compressor and contactor and raises electric bills by 10 to 20 percent. Second, poor humidity control is biggest problem, AC removes humidity only when running continuously for 15 to 20 minutes, so short cycles do not dehumidify, leaving indoor humidity at 60 to 70 percent that feels clammy and cold, encourages mold growth and dust mites, and causes you to lower thermostat to feel comfortable, using more energy. Third, uneven temperatures with hot and cold spots because air not circulated long enough. Fourth, increased noise from large unit starting and stopping frequently. Fifth, shorter lifespan due to more starts. Properly sized AC runs longer cycles of 15 to 20 minutes that dehumidify and keep temperature even. If your AC is oversized, solution is to use variable speed or two-stage that can run at low capacity, or add whole-home dehumidifier, or on next replacement, perform Manual J load calculation and downsize to correct size.