R-Pro › Field cases › Air conditioning
AC Evaporator Frost/Defrost 'Pop' Sound
Likely causes
Natural noise from freezing/thermal expansion vs fault
Check: Normal: 1–2 'pop/click' during heat-pump mode swap (heat↔cool/defrost), start, or stop. Abnormal: continuous pops during operation = evaporator freezing → diagnose filter/undercharge (separate case). Cabinet plastic cracks from sun/temperature can also pop.
What to do: Normal pop = 1–2 times at defrost cycle or mode switch = resolved by user education. Continuous pop = evaporator frosting → check filter/undercharge (separate case). Cabinet cracks = UV exposure, add shade or replace cabinet. Shade must not block airflow.
Normal pops resolved with user education. Continuous = act now. Cabinet cracks = UV exposure; suggest shade/replacement. Korea = defrost cycle pops are normal — pre-explain to user to avoid disputes.
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