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Blinking Red Light on AC Unit Thermostat: What’s Going On?

the living room of a home where they just discovered a blinking red light on the ac unit

Any time you see a blinking red light in your home it can be stressful. Blinking red lights are often a sign that something is going wrong. If you see this kind of light on your AC unit thermostat, it might not mean that there’s a major problem. The most likely reason that this red light has started blinking is that your outdoor AC unit has shut off. This can happen even if your indoor unit is still running, and some simple issues might be the culprit.

For example, your outdoor AC unit might not be getting the power it needs to run. This can happen if a circuit breaker has tripped or if a fuse blows. If either of these things are the problem, then you should be able to get your outdoor unit working. Simply flip the breaker back to “on” or contact a professional to replace the blown fuse. You might also try resetting the AC unit using the reset button on the outdoor unit.

However, if these steps don’t work, it might mean that you have a more serious issue. At this point, it’s typically best to contact an air conditioning and heating expert. They will inspect your system to determine what issues your AC unit might be having that could be contributing to the problem. Some AC units have coded systems, which means the pattern in which the red light is blinking means something specific. These pros have the specialized tools and knowledge to interpret these lights, figure out what’s wrong and get your system running.

The following are some of the most common issues that might cause the red light on your AC unit thermostat to start blinking.

The Capacitor Has Failed or Is Getting Weak

The capacitor works like a battery in that it stores the energy that the fan in the outside AC unit needs to either run or start—depending on the type of capacitor that’s in your unit. Some types of capacitors power the compressor and the fan. If the capacitor fails or is starting to wear out, then the condenser fan—and perhaps also the compressor—won’t be able to run the way it should. Then, the unit will likely shut down.

When this happens, it’s likely that you’ll need to have the capacitor replaced as soon as possible. This is because bad capacitors can cause additional problems. For example, if the capacitor is weak, it could mean the condenser fan motor will have to work extra hard and could burn out earlier than it’s supposed to. Additionally, depending on the type of capacitor that you have, waiting too long to replace a weak capacitor can also lead to damage to your compressor.

The Condenser Fan Motor Has Burned Out

As mentioned above, a weak or failed capacitor can put stress on the condenser fan motor and cause it to burn out. Other kinds of things that put stress on the motor include improper maintenance, as well as normal wear and tear as the unit gets older. If the motor has burned out, you will need to replace it before the AC unit will start working again.

The Compressor Contactor Is Broken

An AC compressor contactor is like a heavy-duty switch on the outdoor AC unit. When the compressor contactor is working as it should, it turns the unit on and off and provides power to essential components in the unit. However, when the AC compressor isn’t working, it can mean that the fan might stop spinning while the condenser continues to run. Beyond disrupting the functioning of your AC system, this can also lead your condenser to overheat and burn out.

In some cases, you might be able to get the outdoor unit working again temporarily by unsticking or cleaning off your contactor. However, the safest and longest-lasting solution to this problem is to get the contactor replaced by a professional.

There’s a Problem With a Connection Somewhere in the System

If any of the connections in the AC disconnect box are loose or fried, then your AC unit might not run. Some things that can cause this are if a connection gets bumped or if a power surge due to lightning or some other power issue sends an abnormally high level of voltage through the system.

Some of the other underlying issues that might trigger a red light to start blinking on your AC unit thermostat include problems with the high or low pressure or temperature switches, a failed ambient or liquid line sensor or issues with the high or low discharge temperature. For many of these problems, it’s best to hire a reputable air conditioning and heating specialist.

Trying the do-it-yourself route on AC issues can be dangerous. As with any project involving electricity and high-powered appliances, mistakes can lead to shock or even electrocution. However, a licensed AC specialist can take care of any of these issues for you. These pros have the training and special tools needed to quickly and accurately diagnose and fix the AC problem. Plus, they can help keep you and your family safe in the process.

a white kitchen

How to Reset Your AC Unit

As with many things in life, sometimes just turning your AC unit off and on will fix the problems you’re facing. However, you first have to find the right switch on the outside unit in order to reset it. This can sometimes be a tricky task depending on the model of your unit.

For any type of AC unit, the best first step is to turn the indoor thermostat to the “off” position. Then, flip the circuit breaker for your AC unit to the “off” position. Wait at least one minute and then flip the circuit breaker back on and turn on your indoor thermostat. This process will sometimes reset the whole system. If not, you can also try resetting the outdoor component of your AC system.

To reset your outdoor AC unit, first unplug your unit for about 15 to 30 seconds and then plug it back in. Next, look for the little red reset button. You might need to consult the owners’ manual for your unit to find out exactly where the button is. This is because different manufacturers place these buttons in different places. Once you find the reset button, hold it down for about three seconds and then release it. Your unit might restart as soon as you release the button. If it doesn’t, you can try this process again, and if it still doesn’t work, it’s best to contact an AC professional.

If you are having trouble finding the reset button, you can also try manually resetting the system. To do a manual reset, first turn off the power to your outdoor unit, unplug the unit and flip the circuit breaker for the unit to the off position. After you turn off the power, wait at least 30 minutes. Then, turn everything back on in reverse order—plug the unit back in, flip the circuit breaker switch to on and turn on the power switch by the outdoor unit. As with using the reset button, if you still aren’t able to get your AC unit using this manual process, it’s important to contact an AC specialist.

These specialists have the skills and knowledge needed to get to the bottom of the problem. Then, they can make any of the AC repairs needed to keep you and your family cool.

a living room where the homeowners are experiencing bad ac compressor symptoms

Bad AC Compressor Symptoms

The compressor is like the heart of your AC system in that it pumps refrigerant throughout the system and it’s one of the main components that makes your AC work. If the compressor has gone bad, then your AC won’t be able to keep you and your family cool. Some of the main signs that you might have a problem related to the AC compressor include:

  • the compressor won’t turn on;
  • the circuit breaker for the AC unit keeps tripping;
  • your outside AC unit is making weird noises or shaking when it turns on;
  • warm air is blowing out of your vents, even though the thermostat is turned to cool;
  • you find liquid pooling around your AC unit;
  • the air coming out of your vents isn’t blowing as strongly as usual or
  • your electricity bills have suddenly gone up without explanation.

No matter whether your AC compressor is having issues or you’re facing some other type of problem with your AC system, your best bet is to contact an AC expert as soon as you start having issues. An air conditioning and heating specialist can take care of everything for you, so you don’t have to try to deal with this on your own.

ABC Can Get Your AC Unit Running Smoothly Again 

It can be stressful dealing with a blinking red light on your AC unit. Instead of trying to deal with this problem yourself, contact ABC Home & Commercial Services. Our licensed specialists are highly trained. They can get to the root cause of your problem and then make all AC repairs. This way, you and your family members won’t have to worry about your AC blowing warm air or not working at all.

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