5 Possible Reasons Your Air Conditioner is Leaking Water


Addressing water leakage in your air conditioner promptly can prevent potential damage to your home and expensive repairs.

Unfortunately, if you notice water leaking from your AC unit, turn it off until you can identify and solve the problem that caused the leak. Otherwise, you will likely be in for more expensive air conditioning repairs soon. 

If your air conditioner is experiencing persistent leaks or other problems, contact Thomas Hoffmann Air Conditioning & Heating.

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Any air conditioning unit malfunction can be very annoying, especially if you have to interrupt its use and call an HVAC technician to fix it. If you notice water leakage from your indoor unit, unfortunately, it means just that: turn it off until you can identify and solve the problem that causes the leak. Otherwise, you are likely in for more expensive air conditioning repairs very soon. 

Here are the five most common causes of water leaking from your indoor air conditioning unit:

1. The Drain Line Is Clogged

The drain line (usually white) connects your indoor unit to the outside, leading the water from condensation to drain safely. If this pipe is clogged, the water will have nowhere else to go and come out through your indoor unit openings. Algae, dust, mold, and other debris can clog your pipe, which can be prevented by cleaning the pipe with white vinegar every six months. You may consider using a wet/dry vacuum cleaner to unclog a drain pipe or call an HVAC company.

2. The Drain Pan Has Holes or Cracks

The drain pan (or, better said, a pair of pans – one fixed and one removable) collects the condensed water droplets from the evaporator coils. If one of the pans is cracked, has a hole, or is missing completely, the water will not be redirected through the drain line. Check that the pans are in good shape and not misplaced or broken. 

3. The Pump Does Not Work Anymore

If the AC indoor unit is in your basement, one possible problem could be a malfunctioning water pump. This pump pushes the water safely through the drainpipe toward the outside to allow it to be discarded properly. Check if the pump is working at all before you investigate other causes.

4. Poor Maintenance of the Unit (Old Air Filters)

The water leak may be caused by poor maintenance of the unit. If you forget or neglect to replace or clean the air filters, the air will not flow correctly, leading to issues like frozen evaporator coils. When this happens, the drain pan will overflow and leak water indoors. Replace the air filter and check if the unit works properly afterward.

5. Refrigerant Leakage

Another possible cause of the evaporator coils freezing over is a low refrigerant level (most often, air conditioners use freon.) The refrigerant in your HVAC system is not a substance you occasionally add. Its level should always be the same, so a refrigerant leak is an important issue that should not be overlooked. Some units have self-diagnosing functions, but it’s best to call a professional to check if yours doesn’t. 

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At Thomas Hoffmann Air Conditioning & Heating, we pride ourselves in being a locally owned and operated HVAC company. With more than 30 years of experience and a master technician and mechanical engineer as our owner, we can replace, repair, and provide maintenance for your business or home’s HVAC system.

(314) 471-7625

1 thought on “5 Possible Reasons Your Air Conditioner is Leaking Water”

  1. Excellent article! Identifying the reasons behind a leaking air conditioner is crucial for preventing further damage and ensuring efficient operation. This comprehensive guide offers valuable insights into common issues and how to address them. Perfect for anyone experiencing AC problems. Thanks for the helpful information!


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