Our air conditioners are complicated appliances which serve a vital function in our homes. When they are working properly, we hardly think about them at all. When they aren’t, we realize how much we take our cool, comfortable living spaces for granted. When you notice your air conditioner turning on and off repeatedly, you probably realize something is wrong, but you likely have little clue as to why this is happening, much less what to do about it.
There are a few reasons your air conditioner could be cycling on and off. The first and most likely is that your AC unit is too large for your home. When it comes to choosing an air conditioner, you may have fallen victim to a common misconception: the bigger the better. Unfortunately, unscrupulous contractors have an incentive to add extra capacity “just to be safe”, even when you really don’t need it, since that results in higher profits.
When your air conditioner is too big, it pumps a large amount of cool air into your house quickly before abruptly shutting off. This pattern can increase your electricity bill and put a strain on your system’s parts and components, increasing the chances of a breakdown or unnecessary wear and tear. Worse still, a unit that’s too large won’t adequately remove humidity.
Let’s go into more detail about how to right-size your central air conditioner, other reasons your system may be acting up and how to keep your system working effectively and efficiently.
What Size Central Air Conditioner Do I Need?
An air conditioner is a large investment, and the majority of your utility bill goes to heat and cool your home. Choosing the right-sized air conditioner and having it installed properly is important not only to your wallet, but also to the efficiency of your system. When we talk about size, we are talking about an air conditioner’s ability to generate cool air, not the dimensions of the unit.
If you select a unit that is too small for your home, you won’t be able to cool your living areas adequately when temperatures are highest. Oversized systems stay on for shorter time periods, spending a larger percentage of time in a less efficient start-up mode. Shorter run times also diminish the amount of moisture removed from the air and result in less indoor air mixing. Placing a unit in an improper spot, not having enough insulation and faulty ductwork can also impact your system’s efficiency.
An air conditioning contractor cannot simply walk through your home and suggest what size AC unit you need. There are many factors to consider, including:
- How many people live in your home
- How many windows you have, how old they are, whether they are north or south-facing and how well insulated they are
- How much sunshine your home gets
- How much insulation you have and what type it is
- How many skylights you have, if any
- The heat transfer between your walls and through your concrete slab
- What type and where your ductwork is
- How much sun exposure your interior walls get
The smallest sized air conditioner is 1.5 tons and the largest is 5 tons. Systems go up half a ton from one size to the next. Most homes require a ton of cooling for each 600 to 800 square feet. If you have a 2,400 square foot home and ask yourself: How many tons of square foot do I need?, the answer is a system that’s between 3 and 4 tons.
The best way to get the most accurate assessment of the proper sized AC unit for your home is to hire a reputable air conditioning contractor to perform a whole-house load calculation. Installers may perform this service for free as a part of an estimate they generate when you are shopping for a new unit. The contractor may choose to do a whole-house load calculation or a room by room assessment. A whole-house load calculation is best when you only want to replace your AC, whereas the room by room evaluation is best in situations where you are considering replacing the ductwork as well. A reputable technician will gather information and make calculations using a professional software program to take the many variables into account that determine exactly what unit is best to meet your needs.
Air Conditioner Shuts Off Every Few Minutes: What Else Could Be Going On?
If your AC unit is sized correctly but still shuts off every few minutes, you may have a problem with your system’s evaporator coils and wiring. An air conditioner that shuts off every few minutes is short-cycling. Diagnosing this issue requires taking a closer look at different pieces of equipment in your air handler.
Frozen Evaporator Coils
In a split-system central air conditioner, your evaporator coil is found within the indoor unit. The refrigerant in your evaporator coil absorbs heat from your indoor air in your house and cools it as it passes through the expansion valve. When your evaporator coils freeze, they can cause a short cycle and prevent your AC from properly removing heat from your home.
A clogged air filter is the most common culprit for reduced airflow. Having too much debris in a filter causes your system to work harder than it should. If a clogged air filter isn’t your issue, have a trusted AC technician check your unit’s level of refrigerant.
There are a number of electrical problems that could lead to short cycling. Damaged or worn wiring may be keeping your AC system from turning on and off correctly. This type of work is typically best performed by a professional, due to the inherent dangers in dealing with electricity.
My Air Conditioner Keeps Turning Off And On By Itself: Is This A Different Problem?
Still experiencing a problem with how your air conditioner is cycling, and not sure what to do? At this point, your best bet is likely to bring in an experienced professional to help troubleshoot the problem. If you want to exhaust all the other possibilities first, there are a few other things you may want to check.
Dirty Air Filter
As we have already mentioned, most AC troubles can be traced back to a dirty air filter. These important components keep pollution and debris out of your air conditioner. When your filter becomes clogged, the airflow in your system will become impaired. This restricted air flow can cause your evaporator coil to freeze, and will force your unit to work harder than it should to push air through your system. Replace or clean your air filters every thirty to sixty days to keep your system running efficiently.
Incorrect Thermostat Placement
An AC unit’s thermostat measures the temperature around it to help determine when it should power off or on. While less common of an issue, incorrect thermostat placement will prevent your system from getting an accurate reading of the temperature throughout your home.
Your thermostat should be installed a reasonable distance from an air supply vent or window with direct sunlight. Placing your thermostat too close to either of these objects will result in your reading being colder or warmer than it is, sending the wrong signals to your system. An air conditioning contractor can advise you on the best placement for your thermostat.
Air Conditioner Turns On And Off Right Away: Maintenance and Care Tips For Your Unit
Short cycling problems can be prevented, in most cases, by selecting the right AC unit, having it professionally installed and performing routine maintenance. A trusted professional can help answer any of your questions so you understand how HVAC systems work and know when something is amiss. Having your system inspected twice a year (before the start of heating and cooling season) will help extend the life of your unit, spot possible warning signs and make repairs before they turn into costly headaches.
A few other ways homeowners can prevent problems with your air conditioner include:
- Keeping two feet between your outdoor unit and any landscaping, outdoor items or yard debris.
- Changing or cleaning your air filter every thirty to sixty days.
- Cleaning your condenser coil each year, or as necessary, or have an HVAC technician do this for you.
- Preventing clogs by passing a stiff wire through your drain channels on occasion.
- Straightening your coil fins with a “fin comb”, as needed.
ABC Is A Trusted, Full-Service HVAC Provider
Problems with your air conditioner can quickly disrupt your normal routine. Whether you have a wrong-sized unit, need a repair done or want to make sure your next system is installed correctly, ABC Home & Commercial Services can help. Our trained and experienced HVAC professionals can resolve any heating and cooling issues you may encounter. We will respond quickly when you have a problem and are available for routine checks when you don’t to keep your system running at top efficiency. With ABC’s help, you can stay comfortable in your home, all year long.