AC Stops Immediately After Start — Protection Circuit Trip

Identify protection — high/low pressure, overcurrent, overheat, freeze

Check: Read PCB error code (manufacturer manual / self-diagnostic mode). High-pressure cutout (typically 4.15 MPa R-410A — manual prevails) = condensing pressure spike → check outdoor fan, clearance, overcharge. Low-pressure cutout (typically 0.05–0.10 MPa) = low suction → undercharge, EEV blockage, frozen coil. Overcurrent trip = check start capacitor, compressor load.

What to do: Apply per-error code procedure from manual. Protection circuits behaving correctly = restart only after root cause resolved — forced retry damages compressor. Monitor 30 min after restart + log pressures and current.