My AC Turns on and Off, Is That Normal?

If your AC system isn’t working properly, you’re bound to notice it in one way or another, especially during the hot summer months. One common sign that an AC unit is malfunctioning is short cycling, or the unit turning on and off unexpectedly.

Short cycling means that the AC unit’s cooling cycle is ending prematurely and then starting up again, with 5 to 10 minutes between each restart. If you notice that your AC system is short cycling, a call to your local HVAC technician may be in order as there is most likely something wrong with your system.

Causes of Short Cycling and How to Fix Them

Though short cycling is a sign of malfunction in AC units, it could be pointing to a variety of easily fixable issues. Here are some of the most common causes of short cycling:

Malfunctioning thermostat. Your thermostat might not be sensing your home’s temperature accurately and therefore communicating false information to your AC unit, causing it to stop and start. Try replacing the batteries in your thermostat; if nothing changes, call an HVAC technician to diagnose the problem.

Dirty or old air filter. AC units need to have their air filters replaced often in order to function at maximum capacity. Typically, homeowners can change the air filters in an HVAC system without the assistance of a technician.

Low refrigerant or a refrigerant leak. Refrigerant refers to the coolant used in your system to absorb heat and disperse cold air. If the refrigerant levels are low or a leak is occurring, it may be causing your AC’s compressor to malfunction, in turn causing short cycling. Maintaining proper levels of refrigerant is very important, as low refrigerant levels can lead to other HVAC issues such as frozen coils.

Oversized AC unit. If your AC system is too large for your home, it might cool the entire building too quickly and then automatically shut off more quickly than it should. Though this might not seem like a problem, an AC unit that is too large for the space will provide uneven cooling, excessive wear and tear on the machine, and higher energy bills. An HVAC specialist will be able to provide an expert opinion on your AC unit size.

Electrical issues. In some cases, the AC unit itself isn’t causing the short cycling; rather, a poor electrical connection is the culprit. Check any wires and circuit boards attached to your unit and thermostat to make sure nothing has become detached or switched off.