Why Does My AC Shut Off Every Few Minutes?
November 18, 2021
Is your AC turning off and on by itself? If so, your system may have a problem called short cycling. Short cycling is when an air conditioner runs for short periods of time, turns off, then turns back on frequently.
Hearing your AC turn on and off every few minutes is more than just annoying. It can raise your energy bills, cause wear and tear on your AC, and shorten your system’s lifespan. Since short cycling causes expensive damage, you’ll want to fix whatever is causing the issue ASAP.
In this article, we’ll look at the following common culprits of short cycling and what to do for each:
- Oversized air conditioner
- Poor airflow
- Refrigerant leak
- Thermostat location
- Frozen evaporator coils
If you want to skip the DIY troubleshooting and go straight to the pros, contact Red Cap Plumbing & Air for an AC repair in Tampa.
Oversized air conditioner
AC size is a key part of getting the right cooling system for your home that runs smoothly. Meanwhile, if you install an oversized AC, it will cool your home quickly and then promptly shut off.
This never-ending cycle of starting up and shutting down leads to:
- High energy bills: ACs use a great deal of energy to turn on. Because oversized ACs are continuously restarting, they consume more energy than an AC that isn’t short cycling.
- Increased humidity: In addition to cooling a home, ACs can absorb moisture from the air—if they run for long enough. An oversized AC doesn’t have time to efficiently pull moisture from the air since it cools in short spurts, leading to higher humidity levels in your home.
- Uneven hot and cold spots in your home: Short bursts of air can make your thermostat think the whole home is cool. But, you will likely notice some rooms are cooler than others because the unit can’t cool each room in your home at the same level.
- Shortened AC life cycle: An air conditioner that’s always shutting off and kicking back on can lead to significant wear and tear on its motors. Over time, this wear and tear can shorten the system’s life cycle.
What to do: If your AC isn’t the right size, contact an HVAC expert to perform a cooling load calculation for a new system. To determine what size AC your home needs, a technician considers many factors—such as your home’s square footage, number of doors and windows, insulation levels, and geographical location—during the sizing calculation. Avoid hiring someone who doesn’t perform a cooling load calculation, or you could end up with another incorrectly sized unit.
Your air conditioning system cools your home by removing warm air, cooling it, and blowing it back throughout the house. Basically, the process of cooling a home relies on enough airflow entering your system.
If something blocks the flow of air, your AC needs to go into overdrive to make up for it, which could result in it overheating. And when your AC overheats, it shuts off to give the system a chance to cool down. Once cool, it turns back on again, and the vicious cycle of short cycling continues.
So, what causes problems in your system’s airflow? Poor airflow might be due to:
- A dirty air filter: When an air filter gets clogged with dirt and other debris, it restricts airflow to your air conditioner. It can also lead to frozen evaporator coils, which we’ll cover later on.
- Leaks in ductwork: If your ducts have leaks in them, air escapes to areas it’s not supposed to. The wasted air drives up your energy bill and can cause your system to turn on and off frequently.
- Blocked vents: Air can’t move freely throughout your home and in your system if you have obstructions in front of your vents.
What to do: First, check your air filter. Change your air filter if it’s dirty and see if your system still turns on and off. If your AC is still short cycling, contact a professional to diagnose and fix the issue.
Refrigerant is the substance that removes heat from your home’s air during the cooling process. Your AC’s refrigerant works hand in hand with the compressor, a component that circulates refrigerant by changing it from a liquid into a high-pressure gas or vice versa. Normal refrigerant levels stabilize the pressure in your system.
If you have a refrigerant leak, your system’s pressure lowers, which could trigger the low pressure switch at the compressor, shutting down your AC. The compressor is the heart of your AC system, so when it shuts down, so does everything else.
Then, the pressure rises and tells the AC to turn on again, and the fast short cycling repeats.
What to do: Contact an HVAC professional to verify if you have a refrigerant leak. If you do, you need them to fix the leak and recharge the refrigerant. Refrigerant is a harmful substance, so make sure only certified professionals handle it.
Sometimes, it’s all about location. If your thermostat is in a spot that’s a different temperature from the rest of your home, it can think that your entire home is hotter or colder than reality. An incorrect read can cause your AC to turn on and off repeatedly to “correct” the temperature.
Bad locations for a thermostat include:
- Near a window or door leading to the outdoors
- Under a supply vent
- Near obstructions (e.g., bookshelf)
- An area that’s in direct sunlight
These locations are typically warmer or cooler than the rest of your home, and your thermostat turns on or off based on their temperatures and not on the home's average temperature.
What to do: Call a professional to reinstall your thermostat in a location to get a better temperature reading.
Frozen evaporator coils
If you have ice on your evaporator coils, which is the component that houses your refrigerant, you may notice your AC shuts off and turns back on frequently.
Your evaporator coils house a freezing-cold refrigerant. To keep your evaporator coils from freezing over, your AC needs to pull enough heat from your home to run over the coils. If your AC can’t effectively remove heat from your home, your evaporator coils freeze.
The frozen coils then prevent your AC from running properly, which could cause your system to go into overdrive, overheat, and shut off.
Some reasons for ice on your evaporator coils include:
- Dirty air filter: A clogged air filter restricts airflow, which prevents your system from moving enough warm air over the evaporator coils.
- Refrigerant leaks: As we mentioned, a leak lowers the pressure in your system, which can lower your refrigerant’s temperature and lead to frozen evaporator coils.
- Dirty or malfunctioning blower fan: Malfunctioning blowers can’t move enough air over the evaporator coil, which could cause it to freeze.
What to do: First, turn off your AC to decrease the chances of system damage, then change your air filter. Once you restart your system, see if the freezing occurs again. If so, contact a professional to diagnose and fix the issue.
Ready to fix the problem? Contact Red Cap.
In most cases, you need an HVAC professional to address any AC problems that could cause short cycling. If you’re in the Tampa area, look no further than Red Cap for an AC repair.
We’ll send over one of our trusted professionals to help fix whatever is causing your air conditioner to shut off every few minutes. You’ll have peace of mind in no time!
- Posted in:
- Air Conditioning