The short answer
A mini split leaking water inside is almost always a drain problem. The drain line is clogged, kinked or not sloped downhill, or the coil froze and the melt overflowed the pan. Turn the head off, clean the filters and check where the drain hose ends outside. Water dripping from the outdoor unit in heat mode is normal: that’s defrost. If the indoor head keeps dripping after those checks, call before the water gets into the drywall. Mini splits all over Northern Virginia leak for the same few reasons, and none of them fix themselves.
Indoor head or outdoor unit?
Start with where the water is. The outdoor unit makes water on purpose in heat mode. Every so often it runs a defrost cycle to melt the frost off its coil, and the water runs out the bottom. You may see steam too. Both are normal, and heat pump covered in ice covers when frost turns into a problem.
Water from the indoor head is never normal. The head makes water when it cools or dries the air, and all of it is supposed to leave through the drain.
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How the water is supposed to leave
When the head cools, its cold coil pulls water out of the room air. The water drips into a pan under the coil, and a drain hose carries it out the back of the head, through the wall and outside. Gravity does the work, so the hose has to slope down the whole way with no loops or kinks, and its end can’t sit in water. Heads that can’t drain downhill, like most ceiling cassettes, use a small pump instead. When any part of that path stops, the pan fills and spills out the front of the head.
Symptoms, causes and fixes
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| What you see | Usually why | What to do |
|---|---|---|
| Drips from the front of the head while cooling | The drain line is clogged with dust and slime | Check the hose end outside. If it’s clear and the head still drips, the line needs clearing by a tech |
| Water running down the wall under the head | The drain hose came loose at the head, or a gap in the pipe insulation is sweating | Call. The head usually comes off its bracket to fix it |
| Ice on the coil or the copper lines, then a puddle | Dirty filters, or low refrigerant | Run it on fan only to melt the ice and clean the filters. If it freezes again, call |
| Started right after an install or a move | The head isn’t level, or the hose sags inside the wall | An installer fix |
| Ceiling cassette dripping, or a drain code on the display | The condensate pump or its float switch | Pump service |
| Hose end outside buried in mulch, snow or a puddle | The water has nowhere to go | Clear the end so it drains free |
| Outdoor unit dripping in heat mode, with steam | Defrost | Normal |
What you can do before you call
- Turn the head off with the remote so it stops making water.
- Lift the front panel and pull the filters. Rinse them in plain water, let them dry and slide them back in.
- Look for ice on the coil behind the filters or on the copper lines outside. If there’s ice, run the head on fan only until it’s gone.
- Go outside and find the end of the drain hose. Make sure it isn’t kinked, buried or sitting in a puddle.
- Wipe up the water and run the head again. If it drips again within a day, call.
Don’t pour cleaners into the head or push wire up the drain from inside. The coil fins bend easily and the drain fitting can crack, and either one turns a cleaning into a repair.
Drain codes on the display
Some heads tell you the pan is full. On an LG, CH04 means the float switch tripped. On a Pioneer, d4 means the drain pan is full. On a Samsung, code 665 points to the drain pump. A drain code isn’t a reset problem: clear the water and the cause, or it comes right back. Brand by brand: Mitsubishi, Carrier, Daikin, Fujitsu, LG, Samsung and MrCool, Pioneer, Gree and Senville. Every code family we’ve written up is on our error codes and warning lights page.
When it’s the refrigerant
A coil that keeps freezing with clean filters is usually low on refrigerant, and refrigerant doesn’t get used up. Low means a leak, and topping it off without finding the leak only buys a few weeks. That repair takes a tech licensed to handle refrigerant. Newer systems use R-454B, covered in the R-454B refrigerant change.
Why not let it ride
A slow drip soaks the drywall and the floor before anyone notices, and the fix gets bigger the longer it runs. If the head is new and still dripping, have the install checked. If it’s an older system and the leaks keep coming, best mini split brands and ductless mini split cost cover the replacement question, and our ductless page shows how we install them.
Book it
A mini split visit starts with our $99 diagnostic, and you get the repair price in writing before anything is opened. Call (703) 997-9757 or book a visit online and tell us the brand and the code or what you’re seeing. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Mitsubishi Electric, Carrier, Daikin, Fujitsu, LG, Samsung, MrCool, Pioneer, Gree and Senville are trademarks of their owners.
Questions people ask
Why is my mini split leaking water inside?
Usually a clogged or kinked drain line, dirty filters that let the coil freeze, or a head that isn’t level. Clean the filters and check the drain hose end outside first.
Is it normal for a mini split outdoor unit to drip water?
Yes, in heat mode. The defrost cycle melts frost off the outdoor coil and the water runs out the bottom. Steam during defrost is normal too.
Can I keep running a mini split that’s leaking?
Turn it off or run it on fan only until it’s fixed. Every hour it cools, it makes more water, and that water ends up on the wall or the floor.
How do I unclog a mini split drain line?
Check the hose end outside first. A clog inside the line or the pan is a job for a tech, because the head usually comes off its bracket to reach it.
Why does my mini split freeze up and then leak?
Dirty filters cut the airflow and let the coil ice over. If clean filters don’t stop it, the system is likely low on refrigerant from a leak.
