Air conditioner will not turn on at all; no lights or display.

Safety: Always turn off the breaker and unplug the unit before opening any panels.

Steps:

• 1. Check outlet and breaker: Plug a lamp or tester into the same outlet to confirm power. Reset any tripped breakers or GFCI outlets.
• 2. Inspect power cord: Look for cuts, burns, or kinks. If the plug or cord is damaged, replace the entire power cord assembly; do not attempt to tape or splice.
• 3. Access main PCB: Remove the control panel or rear cover to reach the main board. Locate the onboard fuse (often a glass or ceramic cartridge fuse).
• 4. Test fuse: With the unit unplugged, remove the fuse and check continuity with a multimeter. Replace only with the same type and rating if blown. If it blows again immediately, there is a short that needs professional diagnosis.
• 5. Board inspection: If the fuse is good but the unit is dead, inspect the PCB for burnt components. Replace the main control board if the low-voltage power supply section has failed.