I have 2 ductless Comfort Star mini-split units that were installed by a licensed contractor. One of them drips water from the air outflow. The contractor came out, took it apart, wet vacced out the discharge line, but it still drips. I have all the service manuals, and the only recommendation for this problem is to unclog the condensate discharge tube. Self help videos suggest dirty filters preventing cold air from exiting or clogged condensate discharge. Neither of these is the problem. I disassembled the unit, cleaned the drip pan (which was filthy with accumulated wet dust), and figured I had solved the problem. But no, it still drips. Is there a design issue with these units? The contractor will tell me to replace it.

  • is the drip pan overflowing ? or dripping somewhere else
    – Traveler
    Sep 6, 2022 at 18:55
  • Thanks for replying. The drip pan has a drain hose, which is working - I disconnected it from the external drain and am running the drain hose into a pail to remove any possibility of a clogged drain system. If the drip pan is overflowing, I don't know how.
    – AKG
    Sep 8, 2022 at 18:33

1 Answer 1


If you want cold, you get drips. That is the reality of how thermodynamics works.

Every evaporator (or on heat pumps, reversible condenser/evaporator) must have a drip pan underneath it. That is just basic design competence.

The installer must provide provision for that drip pan to drain somewhere. There must be a drain hose and it must be in good working order.

The "good working order" part may be at issue. For instance if it's just a tube exiting the building, that may be getting plugged by mud wasps or other pests. Fitting appropriate guards may be necessary.

If you're in a dry area, try not to create a mosquito paradise. Many desert cities get mosquitos solely because of A/C discharges being handled incorrectly.

  • 1
    OK, sure, the mini-split has a drip pan with a drain hose, connected to PVC piping that exits the house. It is not clogged, but in any case, I disconnected the drain hose and am running it into a pail during the trouble-shooting process.
    – AKG
    Sep 8, 2022 at 18:37
  • @AKG check the routing of the drain hose. Water does not go uphill, although some installers don't get the concept. (the confusing part is syphons do work, but require every part of the hose to be below the entry. Sep 8, 2022 at 18:56
  • Thank you for replying - as noted above, part of my trouble-shooting was to disconnect the drain hose and route it into a bucket. There shouldn't be any problem now with a clogged drain or uphill flow. My next move is to disassemble the unit again, make sure the drip pan is clean and try to run it with the cover off to see where the leak is actually coming from. I also have a second unit which doesn't leak - maybe I'm missing some internal flashing that routes condensation into the drip pan.
    – AKG
    Sep 10, 2022 at 1:33

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