Why Your Mini Split Is Leaking Water (And A Few Fixes To Try)

Mini splits are great for efficient, ductless, room-by-room cooling. The systems comprises two units, one installed indoors and another outdoors, connected by a set of refrigerant lines, power cables, and a drain pipe. However, they're not perfect, and a common issue with mini splits is water leakage. You might notice water leaking from the indoor unit on more humid days.

The most common reason your mini split is leaking water is a blocked or damaged drain pipe. This is the part responsible for draining moisture that condenses around the cooling coil and collects in the drain pan. The drain pipe extends from the indoor unit to a suitable drainage point, usually outdoors. So, if it's clogged with debris, dust, or algae, or it's damaged, water can start leaking from the indoor unit of your mini split. Even a major bend or kink in the drain pipe can impact the flow, and cause water to back up and leak through the unit.

Improper installation is another possible cause. For example, if the indoor unit is not level but tilted to one side or to the front, the water collected in the drain pan may not flow properly into the drain pipe, and start dripping from the unit. Additionally, dirty air filters can restrict the flow of air, causing the area around the cooling coil to freeze. When this ice starts to melt, the excess water may leak through the indoor unit. Low refrigerant levels can cause ice buildup, too. Keep in mind that you could also be dealing with a refrigerant leak. Common signs include a hissing noise and reduced cooling performance. If that's the case, consult a professional immediately.  

If your mini split is leaking, check whether the drain pipe is clogged or kinked. If it's clogged near the outer end, clear the blockage using a wet-dry vacuum cleaner from a top brand. Avoid anything that exerts excess pressure, as it can dislodge connections and damage the pipe. Also, if you notice any unnatural bends, fix those. The drain pipe should ideally have a downward slope to facilitate the flow of water.

If this doesn't work, it's time to inspect the indoor unit. Turn off the mini split and disconnect its power supply entirely. Then, pull out the indoor unit's cover, remove the filters, and wash them thoroughly with warm water or as suggested by the manufacturer. While you are at it, also look for traces of ice buildup around the cooling coil. If you don't see any, check the drain pan for both blockage and damage. This is the small tray right underneath the evaporator coil. If nothing has worked so far and the mini split was recently installed, it's likely that the unit is tilted. While a quick visual inspection may tell you whether the unit is properly mounted or not, you should always call a professional to realign the unit. That's the safest approach.

After the water leak is fixed, you can take a few precautions to prevent the problem from reappearing. You should clean the filters at least once a month. Also, it's important to schedule professional maintenance routines for your mini split once or twice a year. Lastly, if you live in an area where the weather is generally humid, running a dehumidifier alongside your mini split can help as well.