Outside AC condenser unit won’t turn on? 9 Reasons it’s not working

Baby, it’s hot outside. Oh, baby, it’s hot outside.

There are few times quite as bad as when the outside temperature hits 100 degrees, and you want to be inside. However, inside is not a nice place to be either. 


It’s for a very specific reason. If only you could get some cold air there, it would feel phenomenal. In fact, you used to be able to get the sweet breeze going. Your home was your sanctuary. 

However, your home isn’t your sanctuary in the current condition anymore. 

It’s because your outside AC condenser unit won’t turn on. 

But it was working yesterday. What could have gone wrong since then? 

You’ve tried everything, but your AC won’t turn on after flipping the breaker either. Maybe your thermostat is acting weird


You’ve got 3 kids, 2 barking dogs, and a partner who’s about to jump off a cliff. You’ve tried everything, but the AC won’t kick on. 

Everyone in the house is getting more and more frustrated. Frankly, you don’t feel like being there anymore. 

Last week you found a cockroach in the car, and the EPC light came on. You feel like the entire world is against you. 

Maybe you’re even like in a place in the country with crazy humidity outside, like Florida. You’re starting to panic. You felt your blood pressure rising. 

However, there is still hope. You can save the summer and make sure everyone is happy. 

You can look into various things to troubleshoot why the AC isn’t working. We’ll walk you through some of them so you can hopefully restore law and order at home.

There’s no need to freak out. We’re by your side. 

  1. The thermostat is struggling.
new thermostat

The thermostat plays a crucial role in keeping your house cool. It’s in charge of communicating your various wishes to the air conditioner. Without it, the air conditioner will not know if it should keep your house at a breezy 65 degrees or a toasty 85. 

Without a properly working thermostat, your AC is simply confused. It has no way of working. 

What is the screen of the thermostat saying? That’s the first place to start looking. There are issues so simple that it could be batteries that need replacing. 

If you try turning it on and it won’t, that’s the first indication that it no longer has batteries. However, that won’t be a possibility if the thermostat is wired. 

Maybe your thermostat has run its course and it’s no longer operational. Say goodbye to it and have an HVAC technician come and replace it. 

There could also be a range of other issues with it. For instance, you could be thinking one of the following thoughts:

  • Why does my thermostat setting not match my home’s temperature?
  • Why does my thermostat say “wait”?
  • Why does my thermostat say “aux heat”?
  • Why does my thermostat change by itself?
  • Why is my Honeywell thermostat blinking cool on?
  • Why does my nest thermostat say “in 2+ hours”?
  • Why does my nest thermostat say “delayed”?
  • Why is my nest thermostat blinking red

These are all documented issues that could indicate that you will need to address something going on.

Hopefully, it’s only a matter of changing a couple of batteries. 

  1. You need to look at the circuit breaker.

I remember mowing the lawn at one point. My lawnmower would not start. It had worked last time I took it out of the shed, but that day it wasn’t. I could not figure out what was going on with it. 

I ended up ordering a replacement, and it also didn’t work. It was only then that I realized the circuit breaker had tripped. 

When I discovered the circuit breaker had tripped, I corrected the issue. I tried connecting a light to the electrical outlet, and it was working. Both lawnmowers worked perfectly fine from a different outlet, and now the outlet I normally use as well. 

My mind had not crossed the thought that the circuit breaker could have been the issue. I must have connected too many appliances at one point and tripped the breaker. Ask me if I felt stupid for ordering a replacement lawnmower.

The answer is a big resounding “yes.”

Maybe you have also connected too many appliances. Check out the circuit breaker to see what is going on there. It could have also been that you tripped the breaker while cleaning the air ducts

Look at your electrical panel and find the breaker that supplies the AC. What position is it in? If it’s in “OFF” mode, go ahead and give it a flip. If everything is otherwise working, it should restart everything. 

You should be hearing the sweet sound of your AC unit kicking in. Oh, baby, it’s now getting cold inside. 

There’s also the possibility that things don’t go quite that smoothly. There’s the possibility that the circuit continues to trip. When you’ve flipped it back on, it just keeps tripping. 

Your circuit keeps overloading. Stop this very moment. 

The solution isn’t to try and force it to stay on. The electrical panel was constructed to keep you and your family safe. It’s sending you a message. It’s saying, “if you keep going, we’ll have trouble.” 

You’re risking an electrical fire by trying to force it to do something it doesn’t want to do. 

Then the issues could be much worse. You must call an electrician in that situation. 

  1. Plug the condenser unit in.

Whenever something goes wrong, I have a tendency to jump to conclusions. I’m probably already assuming the worst situation is happening. 

Check on the cord that connects the air conditioner. Is the problem so simple that the condenser unit may not even be plugged in? The unit won’t get any electricity if it’s been unplugged for one reason or another. 

It could just be explaining the reason why your AC unit won’t turn on. 

If you have a window unit, this isn’t unimaginable. There’s a cord coming from your AC that should be connected to the power source. It could also be that it’s been chewed through by a pesky rat. When you stop the flow of electricity, there’s a reason why the unit is not working.

If it’s been unplugged, plug it back in. Did it solve the problem? If so, you’re now the lucky recipient of one happy family once again. 

  1. A blown fuse

A blown fuse could also be the reason why the condenser unit has said “no” today. You’ll want to find the fuse box when you suspect a blown fuse. The fuse box is usually not far away from the condenser unit and is usually outside. 

It’s imperative that you turn off the electricity before you proceed with this. We’d say it a million times if it’s what it would take for you to do it. The electricity must always be off when you start dabbling with electrical components.

You could get electrocuted if you don’t do this step. So, turn off the electricity. 

You now want to do a continuity test. You need a multimeter. 

If you don’t have one, we recommend this one from KAIWEETS. It gets the job done and at a price tag that is surprisingly low. We love it!

Pull out the fuses to get started with the test. When you find the one that’s not working, get a new one. They’re very easy to order from Amazon. Find the make and model or take a picture. 

If you can’t wait, go to the hardware store where they should have another fuse. Otherwise, get it online and have it shipped

  1. Have you cleaned the ducts and changed the air filter?

When you don’t do these things, it gets harder and harder to breathe. Well, it’s the case for the AC. It’s a task that’s easily overlooked, but it’s still necessary. 

When was the last time you changed the clogged air filter? A normal family sheds about 40 pounds of dust per year. It’s a statistic I’m not proud of, but it’s true. 

A lot of it will get sucked out of your house and be stuck in the AC unit. You probably didn’t even know that the air ducts have to be cleaned every 3 years. 

Look at the air filter. Maybe it’s full of dust and various types of debris. It’s no wonder it’s struggling. When it’s the case, airflow is not going as it should. 

The coils will freeze, and your AC won’t be providing that fresh breeze to your home. There could be a layer of ice on your coil that keeps the AC from turning on completely.

You want to see whether that’s the case. However, there’s a thing that you need to do first. Your air conditioner needs to be turned off before you venture out to try to check out the issue. 

Once again, turn it on with the breaker. Replace the air filter now and wait for the ice to melt. Avoid turning on the unit while this process is going on.

A blow dryer is an option, but we’d recommend you crack a cold one open and embrace patience. There’s no need to stress. Today’s a good day. If you use a blow dryer, you’ll want to do it on its lowest setting. 

Dirty AC ducts are a common reason when the heat is working but not the AC.

  1. Check to make sure the drain line is not clogged for your AC.

Moisture and gunk can eventually clog the AC drain line. That’s why maintenance is as important as it is. It’s a good practice to pour a cup of boiling water down your drain pipe to keep it from getting clogged.

It’s a thing you’ll want to do roughly every month. But don’t do it while the air conditioner is on. You want to turn it off first on the breaker. No one wants to get electrocuted today!

  1. Motor failure

Your air conditioner will not work without a working capacitor. It’s what charges the motor. As these systems age, it’s not unlikely that the capacitor is going to give up. You’ll be incredibly lucky if it lasts you 20 years, but you could start seeing problems after 15.

Once again, you are going to do a test with a multimeter. You’ll want to shut off the AC so you can get started on the work. Maybe the motor will prove to be doing fine. Then it’s a different problem you are looking for. 

  1. Leaking refrigerant

 You want to get the cooling back on so you no longer have to run around in your bra at home. A refrigerant leak may be another reason you’re not getting that necessary breeze you’re longing for so badly. 

You want to familiarize yourself with what a refrigerant leak looks like and the various warning signs that something’s off. If you see tiny bubbles in the evaporator coil, it’s what it looks like. There’s now a good chance that leaking refrigerant makes your house so hot. 

If you see your electric bill climbing towards the sky, it’s another sign. A hissing sound or frozen coils are other things to look out for. You’ll want to get a refrigerant leak addressed as soon as possible.

Refrigerant poisoning is a serious concern that can arise if this issue isn’t addressed. Refrigerant performs an important duty, but it’s also potentially poisonous. In fact, only licensed HVAC technicians may purchase certain kinds. It’s a safety precaution from the EPA.

  1. Temperature readings that are incorrect.

Your thermostat could be giving you incorrect information, too. A false reading could cause it not to run the cooling cycles it’s supposed to. 

It’s a reason why the thermostat is normally located on a wall facing inside. Temperature fluctuations can arise for various reasons that will make your thermostat struggle. 

Kitchens and laundry rooms can also have significant temperature fluctuations because of the amount of electricity consumed. On your beautiful kitchen floor stands the oven. You can probably imagine the heat it gives off. Your thermostat would then think the kitchen temperature is the overall house’s temperature. 

Move the thermostat to a different location if that’s the issue. If the AC won’t turn on, but the fan does, it’s very likely the condenser isn’t getting the needed electricity, or there is an issue with the thermostat. However, it could also be one of the other issues on this list. 

Hopefully, this has allowed you to troubleshoot why your AC unit is not turning on when you need it the most, but the fan does turn on.


What do you do if your air conditioner won’t turn on?

The easiest option is to call an HVAC specialist to come out. You can also check to see if something has come underdone or if there’s a refrigerant leak. In fact, most of the problems could arise if you were dealing with a travel trailer

Why is my AC All of a sudden not working?

When your cooling suddenly disappears, the thermostat is the best place to start looking. It’s the most common cause of the issue.