A short fan run after shutdown is usually a built-in drying cycle to prevent mould on the coil. But if the fan runs for fifteen minutes or longer, or stops unpredictably, the control path is likely at fault.
SAFETY WARNING
Stop using the unit and contact a technician if you notice burning or electrical smell, breaker tripping repeatedly, or sparking or heat marks.
Many systems keep the indoor fan running briefly after off. This helps dry moisture from the evaporator coil and prevents mould growth.
We confirm the run-on duration matches the model's built-in drying cycle before treating the pattern as a repair case. Normal delay should not be misread as immediate board failure.
If stop commands do not complete correctly, the fan can continue much longer than normal. The pattern may be inconsistent across attempts.
We test relay switching response and board output signals to confirm whether the relay is stuck or the board is not sending the stop command. Approving parts before confirming command path can miss simple control issues.
Power instability or stressed components can cause erratic fan stop behavior with safety signs.
Stop repeated on-off testing. We check voltage stability at the board and inspect relay contacts for arcing or heat damage. Repeated command cycling under unstable power can worsen the fault path.
Some brands include a built-in drying delay after shutdown, which can feel unusual if you are not expecting it.
If this pattern keeps worsening, move to diagnosis early.
Just observe, no disassembly required:
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Describe what’s happening. We’ll work out the likely cause and tell you the right next step.
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