What happens
Moisture forms outside the intended drain path or escapes through a damaged pan or connection.
Typical symptoms
Water appears despite a clear drain; sweating occurs around line covers, joints or the cabinet.
Checks that distinguish this cause
Locate where water first forms. Inspect approved insulation continuity, pan joints and the drain connection, and distinguish condensate from thawing ice.
What can look similar
A concealed drain obstruction can still back up only during sustained load.
Repair direction
Restore specified insulation and vapor sealing or replace a verified damaged approved pan or fitting.
Verify the repair
Verify dry exterior surfaces and leak-free drainage under humid operating conditions.
Equipment-specific limits
Drain lift, hose routing, traps, vents and overflow wiring differ by indoor style and pump. Do not bypass overflow protection or assume a high-wall drain design suits a cassette.
Practice this diagnosis
This cause is a reference topic; it does not yet have a dedicated simulated call. Browse the practice board.
References and applicability
Original HVACSim explanations with manufacturer and instrument-maker references for further reading. These resources support the subject; their model-specific examples are not specifications for every system.
- Senville: R-454B model documentationSeparate installation and service documents for indoor styles and multi-zone generations.
- Haier: Arctic Next Gen service manualAW/1U EH2VHD model examples of inverter, motor, sensor and circuit diagnostics; obtain the installed model manual.
Editorial review: 2026-09-29. Verify the current manual for the installed model.