R-Pro › Field cases › Air conditioning
AC Drain Pump Fault — Forced Condensate Discharge Failure
Likely causes
Check pump and float switch
Check: Water in pan but pump idle = pump motor open or PCB signal fault. Pump runs but no discharge = impeller blocked or check-valve failure. Float switch stuck = false full signal halts system. Verify 12V/24V signal per manual. Pump motor resistance typically 50–200 Ω.
What to do: Clean impeller (remove debris). Motor open = replace pump (usually whole unit, OEM match). Float = clean; replace if permanently stuck. Test: pour 1 L into pan → pump runs and empties. Check discharge hose for kinks.
Drain pump = ceiling-recessed and some wall-mount models. Standard stand units use gravity drain (no pump). Pump fault usually triggers protective shutdown. Pump lifespan = 3–5 years.
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