Problems with your air conditioner can be very frustrating, especially during the middle of summer. If your A/C keeps turning on and off, you’ll want to find out what’s going on quickly.
When I noticed this problem with my A/C, I also found that my Honeywell thermostat was flashing “Cool On,” which was something I hadn’t noticed before. If you’re having similar issues, there are several potential explanations.
When the A/C turns on and off frequently, it’s called short cycling. If it just happens once, it’s not a big deal. But if it continues or happens frequently, it indicates a problem with the unit. The thermostat or a dirty filter could be to blame, or it could be a refrigerant leak. Other causes are more complex, so you may need to call a professional.
How Do I Know When I Have a Problem?
Most people set their A/C to “auto,” select the desired temperature and let the unit take care of the rest. So, it may be difficult to know whether there’s an issue with the air conditioner or not. When your air conditioner is operating normally, it will turn on and off as needed to maintain your preferred temperature inside your home. What’s important to notice is the timing of when the system comes on and goes off.
If the A/C starts running and then, after a little while, turns off, that means the thermostat has reached your set temperature. After some time, when the temperature rises again, the system will come back on and run. This is normal activity.
However, if it comes on and goes off frequently in a short time frame, then you may have a problem. If the cycle is less than about 10 minutes, then your A/C is short cycling. Short cycling is hard on your A/C system and normally means there’s an underlying issue needing attention.
When short-cycling occurs, it could be both a symptom and a cause of other problems, so it’s important to get to the bottom of it as soon as possible. If you ignore it, you could end up dealing with much more expensive repairs, higher energy bills, or you may even need to replace your A/C sooner than you would otherwise.
Factors That Could Be Leading to the Problem
When your A/C keeps turning on and off, it can be very frustrating. It means your system won’t be cooling your home properly, and you’re probably wasting energy, too. Sometimes, addressing the problem is simple and you may be able to resolve it yourself. In other cases, you may need to call a professional. But in either case, here are some easy tings to check first.
Your thermostat is what tells your A/C that it needs to cool the home, and it also lets the system know when it’s good to turn off. If the thermostat is faulty or needs calibrating, it could lead to your A/C turning on and off at the wrong times.
The first thing you can check is whether you have your thermostat set on “heat” or “cool,” and whether you have the fan set to “on” or “auto.” Then, you can check whether the temperature calibration is correct by checking what the thermostat displays against a thermometer.
If there’s a discrepancy, you can try resetting the thermostat or replacing it altogether. If that doesn’t work, you may need to call a professional for an evaluation.
Where you place the thermostat also impacts how well it performs and how accurate it will be. For example, you don’t want to put your thermostat in a closet, garage, basement, or another area that’s not representative of the rest of your home.
A thermostat right next to a door or window can also have trouble properly measuring and maintaining the correct temperature. If any of these apply to you, consider moving your thermostat to a hallway, living room, or other area where external factors will be less likely to affect the temperature readings.
Dirty or Clogged Air Filter
A dirty or clogged air filter is one of the most common culprits for short-cycling. When the air can’t flow properly through your A/C system, it will have to work harder and will have difficulty heating and cooling your house efficiently.
A clogged air filter can also cause the system to run hotter than normal and create excess noise since it won’t be able to move the air through the system like it should. This can impact how often your system turns on and off.
You should change your air filter every 1-3 months, depending on your manufacturer’s recommendations. Some A/C filters last longer, but it’s still a good idea to check them regularly for excess buildp and blockages.
Air Conditioner is Oversized
If the air conditioner is oversized for your home (or undersized, for that matter), it can cause problems for the unit. When the A/C is too big and powerful for the square footage, it will cool the space very quickly, but that means it will only be on for a short time. When the home starts to warm up again, the A/C will turn on again, and there may only be a brief delay in between.
A/C systems work better when they can gradually maintain temperatures, rather than turning off and on again and again. It’s like getting into your car and putting the A/C on “high,” then turning it off a few minutes later. It won’t be long before you’ll need the air on again, so it will become an endless cycle. Instead, it would be best to set the A/C at your desired temperature and let it do its work.
Refrigerant or Freon Leak
If the refrigerant level gets low due to a Freon leak, it can lead to short-cycling and other problems with your air conditioning system. When this occurs, the pressure in the refrigerant lines won’t be sufficient to cool the warm air entering the system. In that case, the
If the refrigerant level gets low due to a Freon leak, it can lead to short-cycling and other problems with your air conditioning system. When this occurs, the pressure in the refrigerant lines won’t be sufficient to cool the warm air entering the system. In that case, the A/C system ends up working harder and warm air starts collecting inside the unit.
Eventually, the system will shut off to rebuild pressure, then as soon as it’s able, it will turn on again. This is short-cycling, and it’s not good for the system. If you suspect this is your problem, you’ll want to call a professional to come check it out as soon as possible.
Airflow is Restricted
Restricted airflow is one of the most common reasons for your A/C to turn on and off repeatedly. When warm air builds up within the unit, the whole system has to work harder which can cause it to short-cycle.
A dirty or clogged air filter is one of the main reasons you may experience this in your home. Obstructions in your ducts or vents can also restrict airflow and cause these problems. Be sure your vents are open and nothing is blocking the airflow to keep your A/C running properly all the time.
A bad or faulty capacitor can cause problems with your A/C system and may lead to short cycling. This happens when the capacitor can’t keep a high enough current to keep the system running. Short cycling is a very common sign that your capacitor may be failing.
When the system continuously turns on and off, it can cause damage to your system’s internal components. Not only that, but the compressor motor or fan motor could also overheat and fail because of the short-cycling if it’s not corrected.
Compressor is Failing
If the compressor isn’t working properly, it may cause your A/C to turn on and off at unexpected times. For example, many compressors are equipped with some sort of safety or shut-off switch that shuts the motor off if it gets too hot. A faulty compressor may overheat and shut off soon after the unit starts running.
If the compressor is iced up it might also cause short cycling and other problems with the unit. When the compressor isn’t working properly, the air won’t flow thorough the system correctly.
Is it Bad to Shut A/C Off Repeatedly?
Turning your A/C off and on won’t necessarily damage the unit, though it could be hard on it, especially if it’s an older system. However, doing this uses a lot more energy than just leaving the system on and setting the temperature appropriately while you’re gone.
Plenty of people want to save money on their cooling expenses by not running the A/C when no one is home. A better solution is to set your system at 78 degrees Farenheit (or higher) when you’re not going to be there.
An alternative would be to install a ceiling fan. Having a fan can make a room feel much cooler as it circulates the air around the room. It will also help your A/C system run more efficiently.
If your A/C is turning on and off repeatedly (like every 5-10 minutes), it could mean there’s a problem. Check the simple things first – thermostat settings, filter, thermostat location, then consider calling a professional if you can’t resolve the issue on your own. Don’t wait for your system to fail completely before having a tech come take a look at it.
Ruben has a diverse background in the home services industry, with experience running a construction company, a kitchen and bath showroom, and a moving and relocation company. This breadth of experience has provided him with a wealth of knowledge and expertise in various areas of home improvement in general and specifically in the heating and plumbing niche.