Why Does My AC Keep Turning On and Off?

Air conditioning systems can develop a pattern of turning on and off much faster than you expect. Often called short cycling, this pattern is mildly annoying and, at its worst, can harm AC performance and efficiency. The good news is that a number of solutions are possible, from relocating the thermostat to cleaning the coils.

What Counts as a Short Cycle?

Especially during your AC’s hardest-working days in summer heat and humidity, a cycle should run 15-20 minutes. A short cycle for an AC is likely to be closer to five minutes. Also, the series of cycles is likely to be close together and frequent. Instead of two or three cycles per hour, the system could cycle five or more times.

Why Is Repeated Cycling a Problem?

Repeated on-and-off cycles wear your air conditioner out significantly faster. In particular, the compressor unit has to power up at the beginning of each cycle. The compressor is arguably the hardest-working component in your AC, and it also draws the most electricity per cycle. Consequently, short cycles reduce an AC’s lifespan while also running up your electric bill. Failure to address short cycling can make your unit work harder and lead to reduced life of your compressor and the need for expensive repairs.

Potential Causes

Most short cycling issues are fairly mundane, but there are many possible causes. The diagnostic process is simple, and you may even be able to address the problem yourself.

Clogged Air Filters

The standard schedule for air filter replacement is one to three months, but high-usage periods can clog air filters quickly. This is easily one of the simplest and quickest DIY options. Locate the filter, pull it, and see if it’s visibly dirty. If it is, replace it.

The short cycling problem could come back within a couple of weeks. If this proves to be the pattern, then you may want to look at an air purification system.

Thermostat Issues

The thermostat is ultimately the thing that tells the AC whether to cycle. If it sits in a sunny location, it can heat up fast and trigger cycles more frequently. Notably, a thermostat might not cause problems most of the year. The sun’s angle changes, and light may only hit the thermostat for a few weeks. That is enough to wreck your summer cooling bill, though. Relocating the thermostat to a shaded spot often solves cycling problems.

Thermostats age and suffer wear and tear, too. People adjust them, leading to loose wires and sensors. Also, folks position furnishings around thermostats. Any of these can cause the thermostat to misread the temperature and trigger more AC cycles.

Low Refrigerant

Refrigerant ultimately handles the heat-transfer process in any air conditioner. If the refrigerant is low or the line has a leak, then the transfer performs poorly. Consequently, the system doesn’t accomplish as much cooling per cycle and may need to run more frequently.

Dirty Coils

The coils in the AC system handle the heat exchange, and dirt reduces exchange efficiency. We recommend professional cleaning to avoid damaging the coils. Also, our technicians have access to industry products that better remove difficult buildup.

Oversized AC Unit

Homeowners often make the mistake of believing that bigger is always better. However, an air conditioner needs to be the right size for your household. A too-large AC unit can cool the area around the thermostat too quickly, triggering a short cycle. The rest of the house stays warm, and then the cool air diffuses into the warmth quickly. This triggers another cycle.

Especially if you just bought a house, an oversized AC could be a surprise waiting for you. The previous owners might have been people who ran a large unit at low temperatures relative to your preferences. Especially if the unit is 10-15 years old, you should consider replacing it. HVAC zoning is a partial mitigation if you want to make a younger, oversized AC work.

How to Avoid Short Cycling

Regular AC maintenance is the best preventative measure for short cycling. A late-spring checkup gives our technicians a chance to check for common problems, particularly refrigerant levels, dirty coils, and thermostat calibration.

Keeping up with AC repair needs is also important. Fixing a failing blower motor can take strain off the compressor, for example, potentially saving a more expensive fix.

Arronco Comfort Air has been in business since 1984, and we employ NATE-certified technicians. If you have questions about an AC unit in Lexington, KY or a nearby area, contact us today.