Mini-split leaking or dripping water inside

A little condensation outside the drain hose in summer is normal; a mini-split pulls water out of the air as it cools. Water dripping from the indoor head or running down the wall is not. Carrier says a mini split usually leaks due to a clogged condensate drain line, a dirty air filter or a damaged drain pan Carrier.

Start here: is it normal?

• Normal: water running out of the drain hose end outdoors while the unit cools.
• Not normal: water dripping from the indoor head, from the louver, or from the joints along the hose. Trane notes a mini-split should not leak water during heat mode Trane.
• Winter note: if the outdoor unit is heating and defrosting, water and steam outdoors are expected. See the cold weather guide.

Common causes and what to do

Step by step: what to check yourself

1. Switch the unit off with the remote. If water is near the wiring or the outlet, switch it off at the breaker too.
2. Catch the water with a towel and a container so it does not reach the wall or floor.
3. Open the panel and check the filter. Wash and fully dry it.
4. Look for ice on the coil. If you see frost, leave the unit off until it thaws.
5. Go outside and look at the drain hose end. It should hang free, not kinked, not buried and not full of debris.
6. Check the level. A head that tilts forward can spill past the pan. That is an adjustment for a technician.
7. Restart on fan mode. If the drip stops, it was likely a frozen coil from low airflow. If it returns in cooling, stop and call.

When to call a technician

Carrier recommends professional service when a condensate blockage cannot be safely cleared by the homeowner Carrier. Call if the leak is persistent, the pan looks cracked or corroded, the coil keeps freezing, you suspect low refrigerant, or the system is new. For a new install, the installer should fix a slope or drain problem.

Keeping it from happening again

• Wash the filters on schedule. A dirty filter is the usual start of a freeze and drip.
• Keep the drain hose end clear of snow, leaves and soil. In winter, keep it above the snow line.
• Book a deep clean every year or two so the pan and drain are not caked with dirt.
• The EPA tells owners to keep air conditioning drip pans clean and the drain lines unobstructed and flowing EPA.
• Not sure how your system works? See heat pumps in Massachusetts.