If the water is near a power point, a light or the unit's wiring
Turn the heat pump off at the remote, then at the switchboard if water is reaching a socket, a light fitting or the unit's cable. Don't take the cover off the indoor unit or touch any wiring. Opening the unit means working close to live parts, and any electrical repair is prescribed electrical work, which only a registered and licensed electrical worker can do.
Indoor or outdoor? That's the first question
Water under the outdoor unit in winter is normal. Mitsubishi Electric NZ says every heat pump runs a defrost cycle from time to time in cold weather, to clear ice off the outdoor unit. Consumer NZ says outdoor units sometimes freeze up and need a few minutes of defrosting before they carry on. EECA puts the point where frosting kicks in at below 5.5 degrees outside. All that melted ice has to go somewhere, so a puddle out there on a frosty morning isn't a fault.
Water coming out of the indoor unit, running down the wall or staining the paint below it, is not normal. Samsung NZ says a little condensation inside an air conditioner can happen depending on the weather, but a severe leak needs an engineer's inspection. If it keeps dripping, Samsung's advice is to stop using it and book a professional before the water does any damage.
Why indoor units drip
Samsung NZ's FAQ says most leaks come from a blocked or kinked drain hose or the wrong slope. Its fuller list of causes is short, and nearly all of it is about the drain. The indoor unit may not be sitting level, so water overflows the tray. The drain hose may rise above the unit, have a bend in it, or end in water. Rain can run in through the hole where the pipes go through the wall. Or the drain hole has clogged after a long time without cleaning.
Installation matters here. BRANZ says the condensate hose should end in a drain or a garden rather than on a path. Mitsubishi Electric NZ treats getting the drainage right as the installer's job, and keeping the drain system clean as the owner's.
Checks you can safely do yourself
Turn it off and catch the water
Use the remote. Put a towel or a container under the drip and move anything electrical out of the way.
Find the drain hose outside
It's the thin hose that leaves the wall near where the pipes come out. Samsung NZ says it should angle downward and run straight, and its end mustn't sit under water. A hose squashed by a pot plant, buried in bark or ending in a puddle is easy to fix by hand.
See whether the unit looks level
From the floor, compare the bottom edge of the indoor unit with the ceiling line. If one end is clearly lower, water may be spilling over the tray. Leave re-hanging it to the installer.
Notice when it drips
Only after heavy rain points to water getting in through the pipe hole, which Samsung NZ lists as a cause. Only while it's running points to the drain. Jot it down for the technician.
Clean the filters
Samsung NZ's checks include cleaning the unit. Mitsubishi Electric NZ suggests vacuuming the filters with a small brush attachment at each change of season, so do it the way your manual describes. Our heat pump cleaning page covers what an owner can do and what needs a technician.
When to call a technician, and which one
If it's still dripping after those checks, stop running it. Fixing it usually means opening the indoor unit to clear the tray and drain line, correcting the fall on the hose, re-levelling the unit, or sealing the hole in the wall from outside.
Ask for a heat pump repair specialist, or the business that services your unit, rather than a general handyman. Clearing a drain properly means taking covers off near live parts. Some brands want the original business involved first: Hitachi NZ, for one, sends repair and warranty questions to whoever sold and installed the unit.
Renting? Under the healthy homes standards a tenant cleans the heater and its filters where that's easy to do, but where it needs tools, technical know-how or hard-to-reach filters, the landlord is generally responsible. Anything installed to meet the standards also has to be kept in good working order. Let your landlord know in writing, with a photo of the drip.
What you can sort, and what you can't
You can
- Switching it off and catching the water.
- Cleaning the filters as the manual describes.
- Straightening the drain hose outside, or lifting its end out of a puddle.
- Clearing leaves and plants from around the outdoor unit.
- Writing down when it drips, and any error code on the display.
Leave to a licensed installer
- Opening the indoor unit and clearing the tray and drain line.
- Re-levelling the unit or correcting the hose's fall.
- Sealing the pipe hole properly from outside.
- Anything touching the wiring or the refrigerant.
Signs it's more than a blocked drain
- Water inside the wall, or a stain spreading across the wall or ceiling under the unit.
- It's blowing cool air while set to heat, as well as dripping.
- A musty smell that keeps coming back. Samsung NZ says persistent odours may need a professional clean of the indoor unit.
- A blinking light or an error code on the indoor unit, which Samsung NZ says can signal a fault.
What we'd do
Where we'd start
Turn it off, check the drain hose outside and clean the filters. They're quick, and they cover the causes Samsung NZ sees most. If it's still leaking inside after that, stop using it and get a heat pump repair specialist to clear the drain before the water gets into the wall linings. And if the puddle is under the outdoor unit on a frosty morning, leave it be: that's the defrost cycle, not a leak.