What happens
Water from frost removal cannot leave the cabinet or freezes into a flow or fan obstruction.
Typical symptoms
Ice builds at the base, fan clearance is reduced or heating degrades during freezing weather.
Checks that distinguish this cause
Inspect the safely isolated cabinet, mounting height, drainage and any approved pan-heater arrangement. Compare the installation with the model’s cold-climate instructions.
What can look similar
A coil that never defrosts can create similar ice; drain correction alone does not prove the control is healthy.
Repair direction
Restore the approved drainage and mounting arrangement without damaging coils or adding unapproved heat sources.
Verify the repair
Verify water removal, blade clearance and heating through the expected frost/defrost conditions.
Equipment-specific limits
Defrost sequence, fan delays, heaters and low-ambient limits are model-specific. Steam, temporary indoor fan pause or outdoor frost can be normal; persistent ice and repeated faults need evidence.
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.
- Daikin: 17 Series service manualModel-specific sensor and control examples; terminal values and code definitions vary.
- 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.