R-Pro › Field cases › Heat pumps
Cold Air Complaint During Reverse-Cycle Defrost
Likely causes
During reverse-cycle defrost, 4-way valve switches to cooling mode, causing indoor unit to act as evaporator
Check: Inspect with instruments or visually
What to do: Stop indoor fan immediately at defrost start — check PCB parameter or jumper settings (refer to manufacturer service manual)
No logic (including aux heater interlock) to stop indoor fan during defrost, or the logic is faulty
Check: Inspect with instruments or visually
What to do: Verify aux heater installation and check operation (measure heater resistance, normal: several hundred Ω)
Auxiliary electric heater not installed or malfunctioning
Check: Inspect with instruments or visually
What to do: Set 4-way valve switching delay timer — recommend fan stop first, then 4-way valve switch after 3–5 seconds
Excessively high defrost frequency causing perceived discomfort
Check: Inspect with instruments or visually
What to do: Recheck defrost cycle interval and defrost entry temperature settings (typical: 90–120 min intervals at outdoor -5°C)
4-way valve switching delay
Check: cold air discharged for several seconds at defrost start
What to do: If PCB is suspected faulty, replace defrost control board
Fan stop check at defrost start: force defrost mode via remote and verify indoor fan stops within 10 seconds.
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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