Why Does Air Conditioner Turns On and Off Repeatedly

This post may contain affiliate links, which means we may receive a commission if you click a link and purchase something that we have recommended.

To understand why your air conditioner is repeatedly turning itself on and off and why it can be a problem, you first need to understand how it works.

The AC blasts cold air into your home, and that way, it cools it to the temperature set on the thermostat. Some make and models will cool it a couple of degrees lower.

Then it shuts down and stays powered off until the temperature in your house goes a handful of degrees above the set one when it starts to blow cold air again. This on/off cycling has two goals: conserve energy and prolong the AC unit’s lifespan.

HVAC systems have moving parts such as fans, pumps, and compressors. Depending on their quality, they have an expected life span from few thousand hours to few tens of thousands. By inserting breaks in the system’s work cycle, its lifespan gets expanded from a year or so to a decade or more. While being active fewer hours per day, it uses much less energy.

While cycling on and off is a normal way of functioning, AC can start improperly cycling for various reasons. It can start cycling at irregular periods and in very short cycles.

This behavior is called “short cycling” and is a symptom of problems with your AC. These issues can range from minor inconvenience to serious faults in your system. And you should fix them as soon as possible.

How Long does it Take for AC to Turn On?

It depends on several factors. Your AC will turn on when the temperature in your house, more precisely at the thermostat location, reaches a certain pre-set level above the temperature selected on the thermostat. During the hot summer days, this period can be between 10 and 15 minutes under some normal conditions.

In normal situations, this time can be prolonged if your house is warming up slower than expected during the summer days. For example, if your house has thicker or more efficient insulation material than recommended, it can considerably slow down warming up. Also, if the weather is not hot, this part of the cycle will get prolonged.

Winds that may be blowing can also have a similar impact by actively cooling the exterior of your walls. Another factor that can extend the period your AC stays turned off is the rain.

How Long should AC Stay Off Between Cycles?

Depending on various factors, your air conditioner should stay off between cycles 10 to 15 minutes or more under normal conditions. The AC conserves energy by cycling between on and off. It will shut down when the temperature falls below the thermometer level and come back on once it reaches a certain predetermined level above it.

How precisely the temperature will fluctuate during the cycle depends on the AC’s exact make and model. And many external factors can prolong the time between cycles. All factors that can slow down the warming of your house will extend it—insulation, time of the day, outside temperature, winds, rain, and so on.

In case that this time drops significantly below 10 minutes or becomes inconsistent, like getting shorter during mornings and evenings, your AC maybe is not correctly working.

What Causes Air Conditioner to Turn On and Off Repeatedly

There are several reasons why your AC is repeatedly turning on and off. The first and the most obvious reason is that that’s how they function normally.

Your air conditioner will cool your house slightly below its setting and then power off until the temperature rises few degrees above the setting. Once that temperature is reached, it will turn back on.

This helps save energy but also considerably extends the lifespan of your AC’sAC’s parts. But in some situations, your air conditioner may start cycling at a higher pace, either staying on or off for shorter or varying periods of time. This is a symptom of it not working exactly as it should, and can indicate that it is malfunctioning.

So, here are some issues that can cause your AC to cycle improperly and how to go about fixing them.

1. Thermostat’s Placement

The thermostat doesn’t serve just to set the desired temperature to which your AC should cool your house. It also measures the temperature in its surrounding area and regulates the cycle of your air conditioner. It will turn it off when the desired temperature is reached, and turn it on when pre-set temperature above the desired one is around it.

The placement of the thermostat can have a huge impact on the way it measures temperature. If it is placed near some heat source, such as a stove, or is exposed to direct sunlight; it will warm up too quickly which will cause the off-cycle to be cut too short.

Additionally, if it is close to the air went it can be blasted by cold air during the on-cycle. This will then cut short the on-cycle, as it is registering that surrounding air has cooled enough.

Whichever may be the case you will need to change the thermostat’s location. The best location is the interior wall near the center of your house, without excessive air currents.

2. Bad Thermostat

Your AC may start repeatedly and quickly cycle on and off in case of a faulty thermostat. Either if it is erroneously wired or some other defect is causing it to short. It is possible that its internal wiring is faulty in some way. Whichever is the exact cause, an improperly functioning thermostat will cause your air conditioner to improperly function.

The solution for this problem in most cases is obviously a complete replacement of the thermostat, and you should do it as soon as possible. In case that your AC is not cycling properly, it can put too much strain on it causing its lifespan to decrease if not outright create more serious and costly issues. Freezing evaporation coils are the least problem your AC can develop.

3. Frozen AC

In case that the evaporation coils of your air conditioner have accumulated ice on them, you can experience several malfunctions. One of them is rapid on and off cycling. Your AC can become frozen for various reasons, but most of them are causing low airflow around evaporation coils.

Dirty air filters and coils themself are the most common ones, but often the faulty fan or blocked air ducts can be the issue.

To stop your AC from improperly cycling, you first must thaw it and then fix the issue of why it has frozen. Changing air filters per the manufacturer’s recommendations and following other maintenance guidelines will prevent this type of malfunction in the future.

4. Refrigerant Leaks

Your air conditioner uses a special chemical mixture that goes through several changes of pressure and state during the normal functioning of the cooling cycle.

In case that your AC has less than the minimal amount of it, the compressor can start malfunctioning and start rapidly turning on and off. This also causes unnecessary strain on the compressor which can cause damage.

Just toping off your air conditioner with refrigerant is not enough to fix this issue. You also need an AC technician to check over your whole unit to fix the cause of the low level.

5. Uneven Cooling

It is not uncommon that right after you install a new AC unit that it starts short cycling. The most likely cause is that your air conditioner is oversized for your home.

In such a case, it will very quickly and unevenly cool the air inside your house. Such uneven temperatures will equalize relatively fast and trigger the new cycle.

Another cause of uneven cooling can be blocked, improperly sized, or the insufficient number of air vents.

Many larger HVAC companies offer air circulation and house thermal evaluation, and will recommend appropriate AC capacity for your home. If needed, they will also make recommendations for changes to your ducts system. Whether it is a change of vents’ covers or just a proper cleaning of the ducts.

6. Improper insulation

One of the most expensive reasons why your air conditioner may rapidly cycle is the improper or nonexistent insulation of your house. If you have just moved into it and notice that the AC is short cycling, this is a potential issue. The lifespan of the insulation can be longer than a lifetime, but due to various factors, it can start to deteriorate much sooner.

In this situation, you will need to replace it in part or whole. Whether the culprit is improper insulation you will need to hire a specialist that will conduct the thermal evaluation of your house.

Normal functioning of the air conditioners includes periodical cycling on and off. This serves to both decrease the energy consumption but also to extend the lifespan of its parts.

Most of the ACs are designed to work in cycles no shorter than 10-15 minutes. Sometimes your air conditioner may start to cycle in erratic and shorter cycles. It indicates that there are several potential malfunctions of your cooling system.

Leave a Comment