Outdoor Trane air conditioner unit will not start at all; no fan, no compressor, thermostat appears normal.

Safety first: High voltage is present. Turn off the main breaker before opening any electrical panels.

• Check breaker: Locate the dedicated AC breaker in the main panel. If tripped, reset once. If it trips again, do not continue resetting; there is a fault that must be found.
• Inspect disconnect: At the outdoor unit, pull the disconnect and inspect for blown cartridge fuses (if present) or burnt connections. Replace fuses only with the same type and rating.
• Verify line voltage: If you are qualified and have a multimeter, confirm proper voltage at the line side of the contactor. No voltage indicates an upstream electrical issue.
• Check low-voltage call: With power restored, verify 24V is present at the contactor coil when the thermostat calls for cooling. If not, there may be a thermostat or control board issue.

If power issues persist or fuses continue to blow, contact a licensed electrician or Trane technician to locate shorts and replace damaged components.