Many people understand that the air conditioner shouldn’t run too much or too little. For instance, you probably understand that an air conditioner that seems to run nonstop is usually a sign that it’s overwhelmed and merely trying to keep up with cooling demands.
You likely also know that an air conditioner that seems to go on and off every few minutes is short cycling and needs immediate attention.
Unfortunately, not many people know how long an air conditioner should run and how long it should stay off between cycles. Ask a room full of homeowners, and each will have a different answer. Some say it’s 20 minutes, others think it’s an hour, and others have no idea at all.
So, what’s the answer? Let’s find out.
How Long Should an Air Conditioner Stay OFF Between Cycles?
A healthy air conditioner runs for 15 to 20 minutes and then cycles off for seven to ten minutes, depending on several factors. For example, it is short cycling if it stays off for less than seven minutes between cycles. Similarly, you have a problem if your air conditioner stays off for more than ten minutes between cycles.
The Basics: How the AC Cools
Air conditioners keep your home cool by extracting heat from indoor air and dumping it outside the house.
The indoor air handler draws musty, warm air into the air conditioner via an air filter and forces it over very cold refrigerant lines. These lines contain freon, which easily absorbs heat. So, the freon absorbs as much heat as possible from the indoor air, leaving the air cold enough.
The cold air is sent back into your rooms and circulated throughout the home. Meanwhile, the now-warm refrigerant flows back to the outdoor unit of the air conditioner unit, where compression cycles force heat release.
The heat is then forced out of the outdoor unit while the cold-again refrigerant flows back into the home to remove even more heat.
The entire process begins and ends at the thermostat. With the air conditioner switched ON, the thermostat consistently keeps track of indoor temperatures and requests cooling whenever temperatures drop below your setting, typically 78°F.
Then, the thermostat is also responsible for ending the cooling cycle. This usually happens once the room reaches the thermostat setting.
ON vs. OFF Cycles
The ON cycle is the period when the air conditioning system is running and actively removing heat from your home. Meanwhile, the OFF cycle is when the air conditioning system is switched on but idle, i.e., not actively removing heat.
It’s important not to confuse OFF cycles with turning off the air conditioner. Both ON and OFF cycles happen when the air conditioner is switched on and getting power.
Factors Affecting ON and Off Cycles
Unfortunately, air conditioner ON and OFF cycles can be confusing because they aren’t uniform. Your air conditioner may have slightly longer ON or OFF cycles today and shorter ones the next day.
This usually happens for the following reasons;
- Your temperature setting: A lower thermostat setting on a very hot day means the air conditioner may have to run longer. It also means you may experience shorter OFF periods between cycles.
- Load size (size of the room/house): Air conditioners tend to struggle with larger loads while fulfilling smaller loads before time. So, expect longer ON cycles and shorter OFF cycles if your house is big and the opposite for a small house.
- Size of the Air Conditioner: The size of the air conditioner relative to the size of the house maters. An undersized air conditioner (too small for the room) runs longer and has shorter OFF cycles as it needs to work more to fulfill the load. The opposite is true for large air conditioning systems (too big for the room).
- Age of the AC: Finally, older air conditioners are slower (remove heat at a slower rate) than newer units, thus taking longer to reach the thermostat setting. This often means longer ON cycles and shorter OFF cycles.
What’s the Average Length of an AC ON Cycle?
The average length of an air conditioner ON cycle is 15 to 20 minutes. This means that the air conditioner can complete a maximum of three ON cycles per hour. However, this isn’t usually the case as, traditionally, air conditioners cycle off for several minutes between ON cycles.
How Long Should AC Stay OFF Between Cycles?
On average, air conditioners cycle off for seven to ten minutes between ON cycles. This is a highly rounded number, though, as some air conditioners can stay in the OFF cycle for up to fifteen minutes or longer. Nevertheless, a healthy air conditioner will stay close to this range.
My AC Stays OFF Too Long Between ON Cycles: Causes and Solutions
If your air conditioner stays too long in the OFF cycle, you may have a problem. It’s advisable to observe it for at least a full day before concluding.
However, if the problem persists, you should be worried. The following are three things you want to troubleshoot;
The AC is Oversized
This is the main reason air conditioners short cycle. An oversized air conditioner means the unit will reach the thermostat setting faster because it removes significant amounts of heat per unit time. So, it will cycle on and off more frequently.
Unfortunately, an oversized AC may also stay in the OFF cycle for a shorter period because the fan rarely gets enough time to distribute the cool air throughout the room properly. Therefore, the AC must resume duty faster to restore indoor air quality.
Solution: The only solution to an oversized air conditioner is to replace it with a properly sized alternative.
Technical Issues
Are you getting cool air from the air conditioner? Is the air conditioner even set to cool? If the unit stays too long in the OFF cycle, it sometimes doesn’t have much work to do or has a technical issue such as filthy air filters or blocked ducts.
If it doesn’t have much work, the thermostat may be (wrongly) set too high, or the unit is not set to COOL.
Solution: Make sure the air conditioner is getting power, set to COOL, and running on AUTO. Call an HVAC professional if the suspiciously long off cycles continue.
My AC Stays OFF for Only a Short Time Between ON Cycles: Causes and Fixes
If your air conditioner doesn’t seem to cycle off at all or only cycles off briefly before resuming an ON cycle, you may have one of the issues below;
Outside Temperatures are too High
The 7-10-minute average OFF cycle length given earlier applies to typical summer weather. However, if it becomes unusually hot outside, the air conditioner must work harder to remove even more heat from your home.
Remember that air conditioners dump heat in an already very hot outdoor environment. Imagine that it has to dump even more heat in an even hotter environment! the resistance can be massive, causing the unit to run longer and rest (cycle off) less.
Solution: Unfortunately, you can’t fix outdoor temperatures. You can make your air conditioner’s work a little easier by increasing the thermostat setting one or two degrees. Otherwise, it’s out of your control.
Low Thermostat Setting
If it’s not an oversized air conditioner, you want to check the setting on the thermostat. The recommended AC thermostat setting on an average summer day is 78°F. So, the figures above, including the 7-10-minute average OFF cycle length, are based on this average.
Now, imagine if you set the thermostat slightly lower, say to 74°F, perhaps because you’d like to feel cooler. The air conditioner would run longer and “rest” less to meet your higher cooling demands.
Solution: It’s easy to fix this problem – stick to the DOE-recommended thermostat settings. For instance, keep the thermostat to 78°F during the summer.
Other Factors to Keep in Mind
Interestingly, the air conditioner can continue acting up even when you feel you’ve addressed the primary causes of suspiciously long or short OFF cycles. if that happens, check for the following;
- Clogged air filters: Are your filters clean? When did you last replace them? If you can’t recall, it’s time to install a fresh filter.
- Leaking or low refrigerant: Do you suspect low refrigerant? You likely have low refrigerant if the AC produces lukewarm air. You need to call an HVAC technician to fix this problem.
- Dirty or iced-up refrigerant coils: Dirty or iced-up refrigerant coils limit the surface area for heat exchange, which can cause short cycling.
How Long Should AC Stay Off Between Cycles? FAQs
How long should AC stay OFF between cycles?
Generally, an ai conditioner stays off for 7-10 minutes between cycles, though the off cycles can be slightly shorter or longer depending on various factors. If your AC has significantly longer or shorter OFF cycles, you have an issue.
How long should the AC rest?
Air conditioners don’t need to rest as the off cycles between running periods provide enough time for the moving parts to cool down. So, don’t shut off your AC to give it a “rest.”
How many times should the AC cycle per hour?
Generally, an air conditioner cycles two to three times per hour. Each ON cycle lasts 15-20 minutes, and 7-10-minute OFF cycles separate the ON cycles. The cycles can be slightly shorter or longer but not too far beyond the given ranges.
How do I know if my AC is short-cycling?
The first sign of AC short cycling is shorter-than-usual ON cycles. For instance, if your air conditioner typically runs for about 15 minutes but it’s suddenly cycling off after 10 minutes, it’s short cycling.
How long should an AC run to drop one degree?
Most air conditioners drop one degree Fahrenheit in just once ON cycle, i.e., 15-20 minutes. However, others may take up to an hour to drop one degree. It depends on many factors, including the size of the unit, load size, and outdoor temperatures, among others.
Summary
Generally, air conditioners stay off for about 7-10 minutes between cycles. However, the length of the OFF cycles may vary depending on factors such as the load size and technical issues such as the health of the air filter and whether you have enough refrigerant.
Don’t hesitate to call an HVAC professional if you think that your AC stays too short or too long between cycles.