R-Pro › Field cases › Air conditioning
Indoor Unit Drain Backflow — water dripping from indoor unit onto floor or walls
Likely causes
Insufficient drain pipe slope — less than 10 mm per 1 m run
Check: Measure drain pipe slope with spirit level — confirm minimum 10 mm drop per 1 m (1/100 gradient) toward drain. Check indoor unit level (suspect bracket sag)
What to do: Re-adjust bracket to establish correct slope → re-route drain piping (≥10 mm per 1 m) → verify drain hose outlet is ≥50 mm above floor or water surface
Drain pan or pipe sludge blockage
Check: Remove drain pan and visually inspect — black sludge or biofilm blocking 50%+ of flow area. Test drain pipe with borescope or compressed air (0.3 MPa)
What to do: Remove drain pan → pour hot water (50°C) and soak 10 min, then blow out sludge with compressed air → scrub with neutral detergent + brush → confirm pipe clear with low-pressure water (≤0.3 MPa)
Drain pump failure — ceiling cassette model float switch defect
Check: Pour water directly into drain pan to test pump activation — if it does not operate, measure pump supply voltage (12–24 V DC) and test float switch operation
What to do: Remove debris from float switch or replace → replace pump motor unit → after replacement, test with water to confirm normal drainage
When cleaning drain pan, pour 50°C water first, wait 10 min, then blast with air — softened sludge clears much more easily.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
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