The indoor FCU PCB controls fan logic, reads sensors, and manages core indoor commands. When this board behaves abnormally, symptoms can look wide and inconsistent. Because board replacement can be expensive, checks should confirm this path before you commit.
Most likely when
Often not this
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Primary question
How do I tell whether the indoor FCU PCB is truly faulty before approving replacement?
This board sits in the indoor FCU control section.
It manages fan commands, protection logic inputs, and signal interpretation from indoor sensors.
Indoor PCB-related issues often appear as unstable command behavior.
Many FCU issues can mimic control-board faults.
Start with checks that separate board behavior from sensor and airflow problems.
Ask for proof that points to the board itself, not only broad symptom descriptions.
Get urgent help when the unit keeps cycling unpredictably or refuses stable operation after recent service.
Repeated unstable control can lead to recurring downtime and higher repair cost.
Replacement usually makes sense when board-level instability remains after sensor, airflow, and wiring checks are complete.
It usually does not make sense when the recommendation is based on one-time behavior without clear exclusions.
Learn outdoor PCB fault signs, what they can mimic, and what to check before replacement.
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Tell us what is happening. We will assess first, advise one clear next step, and you decide.
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