Why Is My Heater or Air Conditioner Leaking

Drip. Drip. Drip. Do you hear something leaking? If it’s not a sink, it could be your air conditioner or furnace, depending on the season. Leaks are especially common with window unit air conditioners. If you’re wondering why your air conditioner or furnace is leaking water, there could be a couple of reasons for this. The experts at Radiant Plumbing and Air are here to help you diagnose the cause of the leaks in your air conditioner or furnace, and some ways you can fix them.

What to Do When You Notice a Leak

It is common for window air conditioner units to leak. You may even notice your furnace leaking water from time to time. Leaks are not uncommon, but it’s important to make sure your leak is draining in the right direction. Water damage on your floors or walls can cause worse problems down the road.

The most common reason as to Why Your Air Conditioner is Leaking is because it was not installed properly. Window air conditioning units need to sit slightly towards the outside of your home. This allows condensation to drain from the coils to the condensation pan. If your A/C unit is tilting slightly forward, water can easily get backed up and drip inside your home. Adjust the position of your window unit, and see if that stops the leaking.

Common Causes for Leaking Furnaces or Air Conditioners

The first thing you should do when you notice a leak from your furnace or air conditioner is to shut it off. Clean up all the water that you can, and then inspect your unit for the cause of the leak. If a leak is consistent, be sure that it is flowing towards a drain or outside so it doesn’t cause future water damage.


Both air conditioners and furnaces leak because of condensation in and around the unit. Air conditioners have a built-in condensation drain pan that overtime can clog and accumulate water that eventually leaks. A simple fix is to clean the condensation pan with warm water and vinegar.

Condensation leaks in furnaces are common, and the water should flow into the condensate drain line to prevent water damage. If you notice water pooling up, you may find clogs in pipes or the condensate drain line that will need to be addressed.

Dirty Air Filters

A good rule of thumb is to replace your filters every 90 days. This is true for both your air conditioner and furnace. Clogged filters can prevent proper air flow through the unit and reduce efficiency. Occasionally this results in condensation issues in the unit. Replace the filter and see if that stops your leaks.

Internal Issues

If your air conditioner is running constantly, the copper coils that contain the refrigerant may have caught debris and dirt. It’s important that coils be cleaned so that heat is exchanged efficiently and condensation is drained properly. Simply unplug the unit, remove the air filter, and wipe down coils using warm soap water.

For furnaces, cleaning the inside is not as simple. Heat exchangers, plumbing leaks, or humidifiers could be the cause of your leaking furnace. If you’ve tried replacing your filter and you’re still noticing substantial leaking from your furnace, call us right away to further diagnose the problem.

Trust Radiant to Repair Your HVAC Units

Whether it’s help finding which air filter is best for your unit, or calling a technician to diagnose the cause of water leaking, Radiant Plumbing and Air is here to help. Our experienced service team is prepared with parts on hand for the most common air conditioner and furnace repairs. Call Radiant at 833-656-4056 to learn more about how our heating, air conditioning, and indoor air quality services can keep you comfortable all year long.

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