You notice a dark streak on the wall under the indoor head, a puddle on the floor, or water dripping out of the unit every time it runs in cooling. A leaking mini split is one of the few HVAC problems that does visible damage while you decide what to do about it.
The reassuring part: a dripping wall unit is almost never a broken mini split. It's a drainage problem. Your ductless head pulls humidity out of the room, that moisture condenses on the cold indoor coil, and it's supposed to run into a drain pan and out through a small gravity drain line to the outside. Anything that interrupts that path sends the water into your room instead.
How it usually shows up:
- Water dripping or running down the wall from one end of the indoor head.
- A wet patch on the floor or carpet directly under the unit, or stains and bubbled paint on the wall below it.
- Ice visible on the indoor coil behind the filters, followed by a bigger leak once it melts.
- A gurgling or bubbling sound from the unit while it runs.
Turn it off first
Set the unit to OFF at the remote and, if the leak is heavy, kill power to it. Put a towel or shallow pan under the drip. The mini split keeps producing condensate as long as it runs in cooling, so switching it off is the fastest way to stop the water. If the head is above electronics, furniture, or hardwood, move those now.
Why your mini split is leaking water
Roughly in the order we find them:
- A clogged condensate drain line. The number-one cause. The line is narrow and stays damp, and over a couple of seasons room dust combines with algae and biofilm into a plug. Water backs up in the pan and spills over the front of the unit.
- An improperly sloped drain line. A classic on DIY and budget installs. These are gravity drains — the line has to fall continuously from the head all the way outside. A sag, an upward kink behind the wall sleeve, or a level run will pool water and overflow the pan.
- Dirty filters causing a frozen coil. Restricted airflow drops the coil below freezing, so condensate turns to ice instead of draining, then melts all at once when the unit cycles off.
- A failed condensate pump. Heads mounted below the drain exit or on interior walls often use a pump instead of gravity. When it fails or its float switch sticks, the pan overflows.
- A disconnected or kinked drain hose behind the unit. The flexible hose can slip off its fitting or get crushed inside the wall sleeve, usually during an install or re-mount.
- Low refrigerant from a leak. An undercharged system runs the coil colder than it should and ices it up — same melt-and-overflow result, but with weak cooling alongside it.
- A poorly sealed line-set sleeve. If the wall penetration isn't sealed and sloped correctly, rain can track back along the lines into the room. This one shows up after storms rather than with runtime.
The usual fix
Our tech starts at the drain, because that's where the answer usually is: check the pan for standing water, verify the line is clear end to end, and confirm it falls the whole way to its outdoor termination. Clearing a clogged line and flushing the pan solves a large share of these calls on the first visit. From there we check the filters and indoor coil for the airflow restriction that causes icing, test the condensate pump and float switch, inspect the drain hose and the line-set sleeve, and read refrigerant charge if the coil has been freezing. If the line was installed without proper fall, we'll tell you — that's a re-route, not a cleaning.
DIY vs. calling a pro — the honest version
Safe to check yourself first (free):
- Turn the unit off and catch the water. Stopping the damage comes first.
- Pop out and rinse the filters. On almost every ductless head the front panel lifts and the mesh filters slide straight out. Rinse, dry fully, and replace them — monthly in heavy-use seasons.
- Find the outdoor end of the drain line, usually a small flexible tube coming out of the wall near the line set. Check that it isn't crushed, kinked, buried in soil, or plugged. Clearing that end sometimes releases the whole backup.
- Look for ice on the coil behind the filters. If there's ice, leave the unit off and let it thaw completely before anyone can diagnose it.
- Check the drip path. Water from the line set rather than the unit body may just be uninsulated piping sweating — a simpler fix.
Call a pro when:
- The leak comes back after you've cleaned the filters and cleared the outdoor drain end.
- Water appears whenever the unit runs, which points to a sloped-wrong or disconnected line inside the wall.
- Your system uses a condensate pump and it's silent, buzzing, or the pan is full.
- The indoor coil ices up repeatedly, which usually means airflow or refrigerant.
- You see wall staining or soft drywall — a sign water has been getting in for a while.
Do not blow out a drain line with high pressure, pour bleach into an indoor head, or open the unit's electrical side. Refrigerant work is licensed-tech only (EPA 608).
What it costs in the Bay Area
Mini split repairs vary by the part. In our pricing, a condensate pump or drain repair runs about $110–$350 — which covers most leaking-head calls, including clearing and re-terminating a drain line. A control or comms board is $220–$700, and a refrigerant leak repair plus recharge is roughly $180–$700 if icing traces back to low charge. A drain line needing a re-route is quoted after the tech sees the run. We charge a diagnostic fee that's credited toward the repair when you approve the work, and you'll always see a flat, upfront price before we start — no surprise line items.
Get the dripping stopped
Triton repairs ductless mini splits, central AC, and heat pumps across the East Bay, Tri-Valley, and Peninsula — Hayward, Union City, Pleasanton, Livermore, and Dublin, where ductless heads do the heavy lifting through inland summers. Same-week (often same-day) appointments and licensed techs.
Book online or call (888) 993-5699. We'll find where the water is escaping and fix the drainage, not just mop it up.
Related pages
- HVAC Repair in the SF Bay Area — our full heating & cooling hub
- Mini Split Not Cooling — weak or no cooling from a ductless head
- AC Leaking Water — the central-system version
- Mitsubishi Mini Split Repair — brand-specific service
Frequently asked questions
Why is my mini split dripping water from the indoor unit? Almost always a drainage problem rather than a broken system. The head condenses moisture out of the room air, and if the drain line is clogged, sloped wrong, kinked, or disconnected, the pan overflows into your room. Dirty filters that freeze the coil and a failed condensate pump are the other common causes.
Can I fix a clogged mini split drain line myself? You can safely check the outdoor end of the drain tube for a kink, soil, or debris, and you should rinse the filters. Beyond that, leave it alone — blowing high pressure into the line or pouring chemicals into an indoor head can push the plug deeper, damage the pan, or wet the electronics.
Is it safe to run a mini split that's leaking water? No. Every hour it runs in cooling adds more condensate and more damage to your wall, floor, and anything below the unit. Turn the head off, catch the drip, and have it looked at.
Does ice on my mini split mean it's leaking refrigerant? Not necessarily. Dirty filters and restricted airflow cause icing far more often than low refrigerant does, and either way the melt overflows the pan. Clean the filters first; if the coil keeps freezing with clean filters, the charge needs checking by a licensed tech.
How much does it cost to fix a leaking mini split in the Bay Area? It depends on the cause: a condensate pump or drain repair runs about $110–$350 and covers most leaking-head calls, a control or comms board is $220–$700, and a refrigerant leak repair and recharge runs roughly $180–$700. A drain line needing a re-route is quoted on-site. We credit the diagnostic fee toward the repair and give you a firm price before any work begins.