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3 causes of a leaking AC

An AC unit sits atop a splash of water

The cooling relief of air conditioners saves us every summer. But if your unit starts to leak like melting ice, should you be worried? While the solution may be simple, your AC unit leaking fluid isn’t something to be ignored. Keep reading for common causes of AC leaks and how to address them. 

Pro Tip: Refer to your owner’s manual. When in doubt, bring a professional out! 

Reason #1: Frozen evaporator coils 

Your AC unit’s evaporator coils can freeze, often due to the following concerns:

  • They need more refrigerant
  • It’s time for a new air filter
  • The coils need a cleaning

Take the steps below to stop the leak in its tracks!                                                                                                                                                                                                                              


In alignment with your manual’s instructions and AFTER turning the unit off:

  • Add refrigerant (This part should be done by an HVAC professional)
  • Replace the air filter or clean it with mild soap and water on a microfiber cloth, and
  • Clean the coils.

Pro Tip: Let everything dry completely before replacing any removed/open parts and turning the unit back on. 


An HVAC tech fixes an AC unit


Reason #2: The condensate drain line is clogged

A clogged condensate drain line is one of the most notorious signs of a leaky A/C unit, the causes of which can include: 

  • Clogging by debris, dirt, and/or algae
  • Water and gunk getting backed up in and overflowing the drain pan
  • This water and gunk flowing back into the home or foundation                                                                                                                                                                                                                        


To unclog the condensate line, TURN OFF your AC unit and open the service valve to drain any water. Then, pour one cup each of water and vinegar down the line (via the access port) to knock out any lurking mold, bacteria, or deposits. 

After waiting a half-hour, flush the line with water before closing the service valve, turning the A/C back on, and giving it a go!

Reason #3: Improper installation

If your AC unit or condensate drain line hasn’t been installed properly, or if the two are misaligned, the unit can leak, potentially causing damage.

Water damage can contribute to mold growth, water damage, and an increase in your electric bill. Refrigerant leaking from air conditioner can overwork your AC unit, and the gases may cause respiratory harm.                                                                                                                                                                                    


Improperly installed appliances are best handled by a professional. 

Pro Tip: If you’re moving into a new home, make sure you review your home's systems and appliances before signing on the dotted line! Once you’ve resolved the issue, practice regular AC and HVAC maintenance to keep the relief going safely for years to come.

Happy cooling!