Why Your Air Conditioner Won’t Cool Below 80 (+5 Fixes)


Why, why . . . WHY?

I’ve been there. About to scream because you have your thermometer set to 75 but your air conditioner won’t cool below 80. And you’re so tired of being hot.

The good news is that as with most HVAC issues there is a list of possible causes—and more importantly, a list of solutions.

So read on. Hopefully, I’ll have an answer for you, and you can be on your way to cooling down.

5 Possible Causes (and Fixes) For an Air Conditioner That Isn’t Cooling Enough

Before I jump into possible issues, let me get something out of the way.

All HVAC systems are sized based on a variety of criteria. One of the most important is the average temperatures in your area. This is based on historical weather data.

The problem is that many places are seeing temperatures out of the norm. So when you’re living through an unheard-of heatwave in your area, and you desperately need/want your AC blasting . . .  well, you have a problem.

Your air conditioner is no longer the right size and can’t keep up with current temps that are outside of the normal historical averages.

So don’t bother adjusting your thermostat. It won’t help.

Alternatively, you may just need to be patient.

If you’ve just turned the air on and it’s very hot outside, you need to allow your system time. On very hot days—assuming it can reach your desired temps—your system needs to work hard and longer to cool your home. 

Okay, let’s get into the causes and fixes. And I’ll detail some overall fixes at the end of the list.

Main Tips Bonus Tips Dying Thermostat or Batteries Blackout Curtains  Dirty or Clogged Air Filters Open Windows  Dirty Condenser Use LED Light Bulbs  Refrigerant Low or Leaking Invest in a Ceiling Fan  Backed Up or Clogged Drain Line

1. Dying Thermostat or Batteries

Yes, it might be something as simple as this.

Your thermostat may appear to be working fine, but if your batteries have lost voltage there may be problems that aren’t so obvious. Weak batteries will impact system performance even if they have enough juice to power your thermostat.

Or you may need a new thermostat.

Solution: Replace your batteries and see what happens. Is it finally getting cooler? Then you may have found the culprit.

To test your thermostat, you’ll need a thermometer. The Inter­national Association of Certified Home Inspectors recommends taping one on the wall beside your thermostat and letting it sit for about 15 minutes.

After waiting, check to see if the readings match. If they are significantly different, you may need to recalibrate or replace your thermostat.

If you want to get any replacement part – or see how much one would cost – click to enter your model number in the search bar below. Our partners at AppliancePartsPros stock almost every part with free guides on how to install them.

2. Dirty or Clogged Air Filters

Cleaning clogged filters
Clogged filters can burn out your blower motor

Air filters show up in really every article about possible HVAC problems. For such a simple thing, a lack of maintenance can cause havoc.

A clogged air filter will hinder airflow through your system and could ultimately destroy your blower motor. If your fan can’t push cool—or warm—air through your home, it will be more difficult to reach the temps you have set at your thermostat.

Solution: It’s a fairly simple one. Follow the guidelines on your filter and change or clean accordingly.

3. Dirty Condenser

This is another airflow issue.

Your condenser is housed in the compressor, which is the outside unit.  Hot air is collected from inside the house and released via the condenser. But if it’s clogged with dirt, there is no way for that air to be released. So it remains in your home, keeping you hotter than you want to be.

Solution: Do a walk around the compressor and remove any buildup and debris. Leaves, grass cuttings, toys, whatever.  Also, be sure to keep greenery but back away from it. This could be trees, bushes, shrubs, and any garden plants or flowers.

You should also clean the inside, which may seem intimidating. But it’s not! Follow the steps in this video, and you’ll have your AC blowing cold air again.

4. Refrigerant Low or Leaking

Can you hear a faint hissing sound when you get close to your compressor?

Another possible cause for your home not cooling properly is a problem with the refrigerant. If it’s leaking or low, it will lead to low pressure in the line. Low pressure will cause freezing at the evaporator coil, which will stop your system from working properly.

Solution: Unfortunately, this is not a job for the homeowner. Only certified techs are legally allowed to work with refrigerants.

The best you can do if you suspect a leak is turn off your system and call a tech.

5. Backed Up or Clogged Drain Line

When you did that walk around your compressor checking for debris, did you notice a puddle that shouldn’t be there? One that there’s no reasonable explanation for?

You may have a blocked drain line. This will cause the water that collects in the drain pan to rise, then your float will send a message to shut off your compressor. Which means your AC is no longer working.

Solution: This is a job that can be done as a DIY project, but hire a pro if you feel it’s beyond you. If doing it yourself, follow the steps here.

A Few Overall Tips to Help You Cool Down

If you’re living somewhere where you’re now seeing hotter than average temps, you have a few options.

First, buy a bigger AC—just kidding.

Check out your insulation. Take a measuring tape or ruler and determine if you have enough for your area. Assuming, you can access it.

Also, check for air leaks around windows and doors.

Dealing with these issues will help keep your home cooler in the summer and warmer in the winter.

Bonus Tips

You can also try a few of these to provide backup to your under-performing AC.

Blackout Curtains

Not only will these block out the light, but they will also block out the heat from the sun.

Open Windows When the Temperature Drops

I know, you’re probably thinking well, duh! but there is a bit more to add.

If you live somewhere that cools down at night, open your windows. But you also need to create a cross draft to push/pull the warmer air out of your home. Set up a fan to pull in cool air at one window and another to push out warm air at a window on the far side of the house.

Use LED Light Bulbs

These give off way less heat. If you have any incandescent bulbs, don’t use them in the summer. They are a crazy heat source.

Invest in a Ceiling Fan

If you already have one, be sure to have it rotating in a counterclockwise motion. This creates a cool breeze in the room.


I don’t know about you, but I hate being hot. I’d rather be cold any day. Finding out there is something wrong with my air conditioner is like the end of the world. Armageddon. Impending doom.

But the fact that there are simple fixes in a lot of cases is very good news! Let’s recap the things to look for if you have a problem, and some extra tips you can try to cool down.

Check for the following if your air conditioner is having problems keeping up:

  • Dying thermostat or batteries
  • Dirty or clogged air filters
  • Dirty condenser
  • Refrigerant low or leaking
  • Backed-up or clogged drain line

Once you’ve dealt with those, you can also try the following:

  • Blackout curtains
  • Open windows when the temperature drops
  • Use led light bulbs
  • Invest in a ceiling fan

Hopefully, you found the answer to your problem here, and you’ve escaped your own personal Armageddon too. If you’re having trouble with your air conditioner not turning on, explore our article here for some answers.

While you’re here, why not check out our related posts and articles below?

I've been helping homeowners with appliance repair since 2016. Starting out as an enthusiastic amateur, I've since worked with many Appliance, HVAC, and DIY experts over the last 7+ years. My mission is to help fix your appliances and prevent future issues - saving you stress, time, and money. Visit my author page to learn more! Read more