Indoor Unit Water Leak — 5 Causes (Drain/Level/Insulation)

5-cause priority diagnosis

Check: ① **Drain line clogged** (60%): slime/dust/insect at hose end. Vacuum or back-flush with compressed air. ② **Indoor unit not level** (15%): 1cm tilt right = left leak. Spirit level. ③ **Drain pan cracked** (10%): PP material aged after 3 yr → replace. ④ **Insulation missing on liquid line** (10%): condensate → mistaken for ceiling leak. 9mm EPDM (KS F 2839). ⑤ **Reverse slope** (5%): install error. Need ≥1cm drop per 1m from ceiling. Jul-Sep monsoon = peak reports.

What to do: **Diagnosis (15 min)**: ① Slime at hose end? → clean. ② Hose leaks itself? → replace hose. ③ Drips from indoor body? → check level/pan/disassemble. ④ Condensation on insulation? → add lagging. **Prevention**: bi-annual 'drain cleaning' service (₩30k, twice/yr, customer reassurance). Pump models: see condensate pump card.