Unit does not turn on at all; no lights or display on indoor unit.

Safety first: Before opening any covers, ensure the breaker is off.

Steps to try:

• Check breaker and outlet: Reset any tripped breaker. Test the outlet with another appliance.
• Inspect power cord: For portable/window units, check for cuts or burn marks on the cord and plug.
• Check indoor fuse: Remove the front cover and locate the glass or blade fuse on the PCB. Replace only with the same rating if blown.

When to call a technician: If the fuse blows again immediately, there is a short circuit that requires professional diagnosis.