Trane air conditioner displays E3 and outdoor unit does not start or cycles off quickly.

Safety first: Shut off power at the outdoor disconnect and indoor breaker. Confirm the fan has fully stopped before working near the blades.

• Spin test: With power off, try spinning the condenser fan blade by hand. It should rotate freely without grinding. Stiff or seized movement indicates a bad motor bearing.
• Inspect capacitor: Remove the service panel and locate the dual run capacitor (often labeled C, FAN, HERM). Look for bulging, leaking oil, or rust. A deformed capacitor should be replaced with an identical microfarad (µF) and voltage rating.
• Check wiring: Verify all fan motor leads are firmly connected to the capacitor and control board/contactor as per the Trane wiring diagram. Tighten any loose spade terminals.
• Test operation: Restore power and call for cooling. If the compressor runs but the fan does not start, or starts then stops and E3 appears, the fan motor or board is likely faulty.

Replacing a condenser fan motor and capacitor is moderate difficulty and must match Trane specifications. If unsure, have a technician test motor windings and board outputs.