R-Pro › Field cases › Heat pumps

Defrost Entry/Exit Condition Error

Likely causes

Outdoor coil temperature sensor (defrost initiation sensor) faulty or displaced from mounting position

Check: Inspect with instruments or visually

What to do: Check outdoor coil sensor position — verify it is firmly clipped between coil fins, re-secure if displaced

Defrost initiation temperature set too high

Check: defrost rarely occurs (e.g., set at 0°C when it should be -3°C)

What to do: Measure sensor resistance (NTC): compare against reference values (~10kΩ at 0°C, ~20kΩ at -10°C)

Defrost termination temperature set too low

Check: defrost ends too early, leaving residual ice on coil

What to do: Recheck defrost initiation temperature setting — refer to climate zone recommendations (Korea standard: -5 to -8°C)

Timer interval misconfiguration in time-based defrost systems

Check: Inspect with instruments or visually

What to do: Check defrost termination temperature setting — typically defrost ends at +5 to +10°C

Increased sensor contact resistance causing temperature misreading

Check: Inspect with instruments or visually

What to do: Trigger forced defrost mode, then compare sensor temperature displayed value vs. actual measured value

Field tip

Quick sensor check: read coil temp from service parameters and compare with contact thermometer on coil — replace sensor if difference exceeds ±3°C.

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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