Losing power for a few hours could cause problems with your AC, leaving you in a hot and sticky situation, even when the power comes back on!
If you are having trouble keeping your house cooled after a power outage, it’s most likely because of a tripped breaker which can be easily fixed by resetting the breaker or the AC unit. If that isn’t the case, a power surge may have damaged one of the AC components which would require repairs from a licensed HVAC technician.
In this article, I’ll explain what happens to your AC system when the power goes out and how it can affect different system components. I’ll also talk about how you fix each problem so that you can get your AC blowing cool air again.
Why Would a Power Outage Cause My AC to Stop Blowing Cold Air?
When you experience a power outage, all of the appliances in your house will lose power. When that electricity turns back on again, it could send a sudden spike of increased voltage into those appliances causing what we call a “power surge.”
Air conditioning systems have big motors that are not designed to handle these types of power surges. So if your power goes out suddenly, it could cause problems for your system when it is turned back on. Especially if your AC was turned on when the power went out.
I’ve seen power surges result in anything from a damaged compressor to a blower malfunction to complete system failure.
Some of the newer AC systems have even more sensitive parts including circuit boards and electrical components that can go haywire with a power surge too.
The best piece of advice I have to prevent any of these problems from happening is to anticipate the power outage. Since damage is more likely to happen to your system if your AC was turned on during the power surge, turn off your system at the first signs of a storm.
There are also several different types of surge protectors on the market that are specifically made for air conditioning units. If you live in an area that experiences frequent power outages or storms, you may want to invest in one of these.
Why Has My AC Stopped Blowing Out Cold Air
The most obvious sign that something is wrong with your air conditioner is when it doesn’t blow cold air. If it happens after a power outage, the sudden loss of power has likely affected your AC system.
Let’s take a look at a couple of things that could happen to your AC after a power outage that would make it stop running properly, and what you can do to fix them.
The first thing that I recommend checking after a power outage is whether or not one of your main circuit breakers has tripped. Your AC system will have one breaker for the external components and another breaker for the indoor components. You can find the breaker switches in your main breaker box and they should be clearly labeled.
If the outdoor breaker trips but the indoor breaker doesn’t, you could find that your AC is still running, but is blowing out warm air since the outdoor components are the ones responsible for actually cooling the air that runs through your system.
If a tripped breaker is the only reason your AC isn’t working properly, consider yourself lucky because there is a quick fix that does not require the help of an HVAC professional. Simply reset the breakers by turning both of them to the “off” position, waiting a few moments, and then turning them back to the “on” position.
The next thing I recommend checking is your fuse box. Usually, this is mounted on the outside of your house.
Inside the fuse box, you will see two red lights. If either one of them is lit up, it means that you have a fuse that needs to be replaced.
This too has an easy fix that does not require the help of a professional. To replace the fuse, pull on the metal handle to remove the fuse box, replace whichever fuse is blown, and replace the fuse box by pushing it back in.
Power surges can also cause the capacitor to fail. The capacitor is responsible for starting the AC compressor.
If it is damaged during a power surge, the compressor won’t be able to start back up and without the compressor, the entire cooling process is interrupted.
You can find the capacitor by removing the cover plate on the side of the compressor. Once you’ve removed the cover plate, look for a metal cylinder about 3 inches long and 2 inches wide with three wires coming out of it.
If it is blown, you will likely see an oily substance leaked all over the compressor. Unfortunately, if you have a blown capacitor, it’s not as easy of a fix as the previous two problems and I would recommend having a trained HVAC professional come out to replace or repair it.
The compressor is an important component in the cooling process and if it goes out, so could the cool air. Let me explain a bit about how this could happen.
Your AC cools by removing warm air from the inside of your house and directing it over the evaporator coil which holds liquid refrigerant. When the warm air passes over the coil, the refrigerant absorbs the heat and turns into a gas. The compressor then has to change the pressure and temperature of the refrigerant in order to allow cool air to continue through the system and back into your house.
So think about your AC system as one flowing process. When the power goes out, the compressor stops running and the refrigerant in the unit will stop circulating through the evaporator coil which means no cool air coming from your AC.
You can try to get the compressor working again by resetting the unit, but if it has been damaged due to a power surge, your only option is to replace it which could end up costing anywhere from $1500-$3000.
Should I Reset My AC after a Power Outage?
Yes, if you’ve just experienced a power outage and your AC is not turning on or is turning on but blowing out warm air, try resetting it before calling an HVAC technician to come out and assess the problem. A simple system reset might just do the trick!
Some AC systems have a rest button that could be either on the inside or outside unit. But if your system doesn’t have one, or you just want to be sure the job is done right, here is how you can manually reset your AC:
1. Turn off your thermostat – Go to your thermostat and turn it to the “off” position. that way the system will get the message to stop cooling the air.
2. Reset your breaker – Just like I mentioned before, you should have two circuit breakers located in your main breaker box that control your air conditioner. Flip both of them off and then on again to reset them.
3. Wait it out – I always tell people to wait a few minutes before turning their breakers back on. Especially if you just experienced a power outage. Your system just went through a lot, so giving it 30 minutes to rest and reboot before starting back up again will be beneficial to all the components in your system.
4. Turn it back on and cross your fingers – Once your breaker is back on, go back and turn on the thermostat. Your air conditioner should be back up and running at this point. If it’s not, there could be some damage to one of the parts as I mentioned above.
Can a Power Outage Permanently Damage My AC Unit?
The power surge that happens after a power outage can potentially damage any appliance (even ductless Mini-Split units) that uses electricity, including your AC system.
In fact, experts say that power surges can cause serious damage to appliances, computers, and even electrical wiring.
A power surge isn’t always caused by lightning strikes. Sometimes it’s because of something simple like turning on a fan or opening a refrigerator door. Other times, it can be a sign of bigger problems, like a faulty breaker.
So, if you’ve been hit with a power surge, you’ve reset your AC system with the above, and your AC is still not turning on or it is blowing out warm air, I would say that it’s time to call a professional HVAC technician to help diagnose fix the problem.
In conclusion, power outages happen from time to time. They usually last anywhere from a couple of minutes to a day or two, depending on where you live.
However, because most homes aren’t equipped with backup generators, these outages can cause power surges which can cause serious problems for important equipment around your house. For starters, they can leave you without air conditioning during the hottest part of the year.
Fortunately, there are things you can do to prevent this from happening like turning off your unit as soon as the storm comes, or investing in a surge protector for your system.
Hopefully, my tips in this article can help you get your air conditioner back up and running. And save your air conditioner from permanent damage due to a surge.
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.