10 AC Troubleshooting Tips for When It's on the Fritz

Amy Pawlukiewicz
Written by Amy Pawlukiewicz
Updated July 26, 2022
Homeowner lowers temperature on the thermostat
Photo: Angelov / Adobe Stock

Is your AC acting up? Keep a cool head and try these nine troubleshooting tips before calling in a professional.

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Air conditioner problems can get you hot under the collar, especially if they happen during the peak heat of mid-summer. You rely on your AC unit to keep you and your household comfortable, so it makes sense that you’d want to get to the bottom of any pesky AC issues as soon as possible. 

This guide tells you nine common problems your AC system might have, how to troubleshoot them, and when to call in a professional. 

1. Your AC Is Not Blowing Cool Air

A nice, warm breeze can be lovely—but not when it’s coming from your air conditioner. If this happens, lower your thermostat five degrees and see if the air cools. If that doesn’t work, there are one of a few possible culprits:

  • The evaporator is dirty

  • The air filter is dirty

  • Refrigerant levels are too low

Scorching hot days can also impact your unit’s effectiveness, especially if you’re trying to cool your house to 65 degrees when it’s 100 degrees outside.


Clean your evaporator (or hire a pro to do it). Make sure you’re changing your air filter every month or two, depending on your climate, pets in the home, and allergy sufferers. Before adding refrigerant, have a professional look at your unit to make sure it’s not leaking.

2. Your AC’s Air Isn’t Flowing

This problem can manifest in two ways. First, you may hear your unit running, but no air is coming through the ducts. Second, air is making its way through, but it’s not cold. These scenarios are usually caused by one of three problems.

  • Tripped circuit breaker

  • Worn blower belt

  • Low refrigerant levels


Something as simple as a tripped circuit breaker can cause inadequate airflow, so check your fuse box first. If it’s not your fuse box, you should call in a professional to inspect your system and see if there are internal problems. They’ll be able to diagnose whether or not you have a worn belt or a refrigerant leak.

3. Your AC Is Constantly Turning on and Off

This process is called short-cycling, and it happens when there's a dirty air filter, evaporator, or clogged condenser unit. It can cause severe damage to your compressor. Worst case scenario, your air conditioner is too powerful for your home, and it can't figure out when to turn on and off.


If the problem is a dirty air filter or a blocked condenser unit, thoroughly cleaning your system will take care of the problem. But if those fixes don't work, it's best to have a professional come out and assess your home's cooling needs to ensure you have the correct AC size for your living space.

4. Your AC Is Constantly Running

Though your air conditioner should frequently run during periods of high heat, it’s important that it shuts off from time to time to give your system a break and make sure it doesn’t freeze up. An AC that runs constantly can wear down the components of the system quickly and rack up one hefty utility bill.


The first step is pretty simple here, and that’s to kick up the indoor temperature on your thermostat and see if your air conditioner continues to run. If it shuts off—great—your indoor temperature’s just set too low. If it continues to run, you should call in a pro. The cause could be any number of things, including a broken thermostat, compressor, or electrical parts.

5. Your AC Won’t Turn On

Two kids sitting on kitchen floor eat ice cream
Photo: Denira / Adobe Stock

What if your air conditioner goes out and refuses to turn on? It’s frustrating, but many times, it’s due to a tripped circuit breaker. In some cases, the culprit may be faulty wiring.


Try checking your fuse box to see if the circuit tripped. If you check it out and there doesn’t seem to be any problem, do not attempt to check for problems with the wiring. Whenever you’re dealing with electrical problems, you should call a professional so you don’t end up with a nasty shock or a house fire.

6. Your AC Is Leaking Liquid

Your air conditioner can leak two different liquids: water and refrigerant. Condensation outside of the air conditioner is normal, but if you see brightly colored stains near the unit or water is leaking inside your home, that indicates a bigger problem.


Turn off the unit and call in the professionals. An R-410 or even R-22 refrigerant leak can cause damage to your compressor, which is a costly part to replace.

7. Your Condenser Coil Is Freezing

When you run your AC continuously without giving it a break, the condenser coil could freeze. If your condenser coil is freezing, that can wreak havoc on your utility bill.


Check for ice on the coils. Ice shouldn’t form on your unit, especially not in hot temperatures. A dirty air filter could be the problem (which is an easy fix—just swap it out), but you should still have a pro evaluate your system to make sure nothing major is malfunctioning.

8. Your AC Smells Funky

Your AC unit shouldn’t have a stench. If it does, something has likely gone awry. Two types of unpleasant smells seep from troublesome air conditioners: electrical and musty.  


If you smell an electrical odor, turn off your system immediately and call a pro. You can change your air filter if you're getting a musty or mildewy smell, but the best way to avoid this is to regularly have a pro inspect and clean it to prevent mold.

9. Your AC Is Making Strange Noises

Other than the gentle and oh-so-relaxing whirring sound of the fan, your AC unit shouldn’t make noise. If you hear squealing noises, that’s usually a belt problem.  Grinding noises indicate a motor problem.


Regular maintenance can usually catch these issues before they happen, but call an AC professional if you hear mysterious sounds. These are tricky issues to fix, and you risk breaking the unit if you try to DIY.

10. Thermostat Malfunctioning

If your AC works intermittently or shuts off after a short period of time, you might want to take a look at your thermostat. An unlevel or dirty thermostat triggers short cycling and/or constant running, which severely affects energy efficiency. 

First, check that your thermostat light is on, indicating that it has ample battery power to operate properly. Then, wipe it clean of dirt and debris, which can affect its ability to signal the unit to turn on or off after reaching a certain temperature. If these issues persist, call your local AC repair pro for help.

Additional Maintenance Tips to Avoid HVAC Problems

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