Have you ever woken up in the middle of the night drenched in sweat because your air conditioner isn’t cooling properly? It’s a gross feeling, right?

The whole point behind air conditioning is cooler air, so having one that isn’t pulling its weight is pretty frustrating.

So pay attention, since I’m going to cover the reasons for it and hopefully get you cool again.

Why Your Air Conditioner Isn’t Cooling Enough

There are several reasons why this could happen. The good news is that some of them are easy fixes. The bad news is that some of them aren’t. As Carrier says, “Most homeowners can do some basic troubleshooting and may be able to resolve the issue.”

Homeowner Fixing Air Conditioner
If you take the time to learn the following tips, you will be able to fix most of your AC problems yourself.

1. A Faulty Thermostat

Your thermostat is basically a sensor. If it’s no longer able to detect the temperature of the room and communicate with the compressor then it is incapable of starting—or stopping, for that matter—your cooling system.

Solution. There are a few things you can do to troubleshoot your thermostat.

Check to make sure the screen isn’t blank. If it is, you may need a new thermostat.

Check your batteries. This may be the answer to a blankscreen and any other problems your thermostat is having. Batteries do not need to be completely dead to cause your thermostat to malfunction.

Check all your settings. If you did have an issue with yourbatteries, it could have reset some of your settings, so confirm that it is programmed appropriately.

Confirm that your circuit breakers have not tripped.

Finally, make sure that your thermostat is in an appropriate location, away from direct sunlight or other issues that will increase or decrease the temperature in the room.

Here’s a video that may help.

2. Dirty Air Filters

One of the most common reasons for an air conditioner failing to cool your home is the condition of your air filters. Frankly, dirty filters are the cause of many problems.

It’s critical to keep up to date with filter maintenance. Meaning—depending on the type you have—you either need to clean or replace them on a regular schedule.

Filters that have been left too long build up a lot of dirt, dust, and other debris. And it clogs the filter, hindering air from passing through. Air your system needs to heat or cool your home.

Solution. Your filters will have a manufacturer’s recommendation on how often to change them, but here’s a secret that may save you a bit of money.

If you have a small family—maybe just you and your partner—and no pets, you can typically get away with changing or cleaning the filter less than whatever the recommends. However, if you have kids and pets you may need to change it more often.

The best thing to do is hold it up to a bright light when it comes time to change it.

Is the light still shining brightly through the filter? Then you can likely leave it for a while before changing it.

However, if you can barely see the light through the dirt, there’s a good chance it needs to be changed more often than recommended.

3. Dirty Evaporator Coil

This coil is inside and located in your furnace or air handler. When dirt, dust, or debris build up on the coil it impacts the efficiency of your HVAC equipment.

In order for heat to be removed from your home, there is a transfer of heat that takes place between the coil and the air that moves over them. A buildup of gunk impedes the process, reducing your air conditioner’s ability to cool your home.

Solution: Here are the steps to clean your coil.

  1. Power off your AC
  2. Access your coil by removing the access panel on your furnace or air handler
  3. Use a spray-on, no-rinse, evaporator coil cleaner
  4. With a soft nylon brush, remove the cleaning solution and dirt buildup
  5. Once clean, replace the access panel and turn your AC back on

Want to see the process in action? Then here you go!

4. Dirty Condenser Coil

Your condenser coil is outside in the compressor unit. And just like the indoor evaporator coil, a dirty condenser coil will impact the performance of your air conditioner.

Since these coils are outside,they are exposed to the elements, and over time dirt and debris will build up on the coil. The more time that passes without you cleaning the coil, the worse the situation gets. And the chances that your home won’t cool properly increase.

The cause is some what similar to what happens with your indoor evaporator coil. The layer of dirt on your condenser coil creates a barrier between the air that’s blowingover the coil and the heat that’s inside the refrigerant moving through the coil.

Solution. Similar to cleaning your evaporator coil, this is a fairly simple procedure.

  1. Turn off the power.
  2. Inspect the coils for any damage. If you do see significant damage, you should probably call a technician instead of continuing yourself.
  3. Using a coil brush, remove any debris from the coil. This could include dead leaves, grass, twigs, or anything else that is blown up against the unit.
  4. If any of the coil fins are damaged or bent—getting hit with hail or anything else can damage the fins—use a fin comb to straighten them out.
  5. Using a hose, lightly spray down the coils to remove any dirt or debris that’s still stuck. Then use a foaming coil cleaner and spray that back and forth on the coil. Let it sit for about 10 minutes and then rinse off.

For those who prefer a visual tutorial, here is a video.

5. Refrigerant Leak

Next, you may have a refrigerant leak. And if this is the issue with your air conditioner, you will need to have an HVAC technician come to fix the problem. Only certified technicians are allowed to service or repair refrigeration issues.

Refrigerant is the fluid that flows through your coils and extracts heat from your home. Problems with the refrigerant line or refrigerant levels will likely cause issues with your air conditioner.

Solution. As mentioned, you will need a certified technician to deal with refrigerant issues, however you can do a little investigating to determine if this is your problem.

Here are five signs of refrigerant problems.

  • Your home is no longer cooling as it used to
  • There is little if any cool air blowing out of your registers
  • You can hear any sort of hissing sound around your unit
  • Your evaporator coils are frozen
  • you’ve noticed a jump in your electric bills

If you feel those points match your situation, you should turn the power off to your air conditioner andcall a technician immediately.

6. Undersized Air Conditioner

Finally, the problem may be that your air conditioner was not sized appropriately for your home.

If you’ve lived in the house since the air conditioner was installed, has your home ever cooled properly? Or if you have just moved in, again, has your home ever cooled properly?

Air conditioners are size based on a variety of criteria. The size of your home, the amount of heat gain, and the average summer temperatures where you live.

That sounds like a very simple equation, but the problem is many HVAC companies simply base equipment sizes on approximates, without getting into the nitty-gritty of doing a proper load calculation.

Solution. If your system is undersized, there really isn’t a lot you can do about it.

You have a couple of options. You can purchase a new air conditioner and make sure that it’s sized correctly, but I wouldn’t recommend this unless the current air conditioner is near or at the end of its life cycle. The average life cycle for a well-maintained air conditioner is between 10 to 15 years.

Your other option is to add fans or do your best to block heat from your home.


It’s a terrible thing on a hot summer day to have an air conditioner refusing to cool your home. Fortunately, as we’ve pointed out, many of the fixes are simple and inexpensive.

To recap, here are the most common issues:

  • Faulty thermostat
  • Dirty air filters
  • Dirty evaporator coil
  • Dirty condenser coil
  • Refrigerant leak
  • Undersized air conditioner

Use the videos and steps provided and hopefully you’ll be on your way to a cooler home in no time.

Thanks for reading through! I hope we had an answer to your question.

While you’re here why not check out the related posts below? Maybe we can answer some other questions as well.