When everything is working correctly, your AC unit should switch on, operate for a while, and then switch off again until the temperature rises above your thermostat setting. On a hot day, this might happen a few times per hour, and on a cooler day, it may happen only once every few hours. On any day, however, your AC unit should not be turning on and off every minute or two. This constant on-and-off is called "short-cycling." It has a number of possible causes. Here's a look at those possible causes and how to address them.

A Dirty Filter

Your AC system has to pull air through the filter in order for it to flow through your ducts. If the filter is dirty, this takes a lot more energy, and it may cause your AC unit to overheat. When it overheats or maxes out its power use, it switches off. Then, it cools off again a few minutes later and switches back on. Luckily, it takes only a minute or two to change your AC filter. (Plus the time it takes to drive to the hardware store for a new one!) Just slide the old filter out, and slide the new one in. If the short-cycling stops, you've fixed the problem.

Dirty Coils and Ice Buildup

Dirty coils can also cause your AC unit to short-cycle, since ice will build up on the coils and begin to block the flow of air. Take a look at your AC compressor unit. If there is any ice buildup on it, turn off your AC system and give the ice a chance to melt. Then, clean the entire unit by spraying it down with coil cleaner. Let the coil cleaner sit for as long as recommended on the package, and then rinse it down with a hose. This should remove any dust or debris on the coils, which will keep them from super-cooling and forming ice. Turn the system back on, and see if your short-cycling problem has been solved.

Wiring Problems

Unfortunately, if you change the filter and clean or defrost the coils and your AC is still short-cycling, there is probably an issue with the electrical wiring that connects your thermostat to your AC unit. A short in these wires or a wire coming loose can interfere with proper communication between the thermostat and AC unit. While this is an easy issue for a qualified HVAC technician or electrician to fix, it is not one you should attempt to fix on your own since you may shock yourself or make matters worse if you make a mistake. Contact your HVAC technician, like Lakeside Heating & A/C Inc., to schedule a repair appointment.