Indoor Unit Drain Pump Malfunction Causing Water Leak

Question

Accepted Answer

Drain pan float switch contamination or seizure — pump non-operation due to poor water level detection. Check: Check float switch manual operation → measure wiring resistance → inspect float area for slime/scale contamination What to do: Clean float switch and verify operation → replace if faulty → thoroughly clean entire drain pan Drain pump impeller blocked by debris — insufficient head causing backflow. Check: Check drain outlet flow rate while pump runs → below normal flow (0.5–2 L/min by model) → measure pump motor current What to do: Disassemble pump → remove debris from impeller and clean → replace pump if faulty → readjust hanger bolts to within ±1mm level Insufficient drain pipe gradient — poor natural drainage causing pan overflow. Check: Measure drain pipe gradient: verify minimum 1/100 or more for gravity drainage → check for sagging sections What to do: Rework sagging sections → secure minimum 1/100 gradient → consider switching to drain pump system

Indoor Unit Drain Pump Malfunction Causing Water Leak

Likely causes

Drain pan float switch contamination or seizure — pump non-operation due to poor water level detection

Drain pump impeller blocked by debris — insufficient head causing backflow

Insufficient drain pipe gradient — poor natural drainage causing pan overflow

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