When your AC won't start during Las Vegas summer heat, follow this quick troubleshooting guide to diagnose and fix the problem before calling for expensive repairs.
Verify it's set to COOL mode, temperature is below current room temp, and display is lit (check batteries)
Go to electrical panel - AC should have a double-pole breaker labeled 'AC' or 'Air Handler'. Reset if tripped.
Look for a gray metal box near outdoor unit - make sure the pull-out fuse block is fully inserted
Go outside - look for small lights on the unit or listen for humming sound (means it has power)
Water overflow in drain pan can trigger safety shutoff - look for standing water near indoor unit
Remove thermostat cover, look for loose wires or corrosion on terminals (common in Las Vegas due to dust)
Turn OFF breaker for 60 seconds, turn back ON, wait 5 minutes, then try thermostat again
Las Vegas heat causes AC to draw more power, tripping breakers. Check main panel AND outdoor disconnect.
✓ DIY fix - reset breaker, if trips again call pro
Outdoor disconnect box contains fuses. Look for burn marks or broken filament inside fuse.
✓ DIY fix - replace with same amperage fuse ($5-10)
Capacitor gives compressor starting boost. Fails often in extreme heat. You'll hear humming but no startup.
⚠ Pro needed - stores lethal charge ($150-300 repair)
Relay switch that sends power to compressor. Contacts weld together or burn out over time.
⚠ Pro needed - requires electrical expertise ($150-250)
Dead batteries, incorrect settings, or wiring issues. Most common cause of "won't turn on" calls.
✓ DIY fix - replace batteries, check mode setting
Float switch detects water overflow and shuts system off. Common when drain line clogs with algae/dust.
✓ DIY fix - clear drain line with wet/dry vac
High or low pressure cutoff prevents startup when refrigerant pressure is abnormal.
⚠ Pro needed - indicates refrigerant issue ($300-800)
Circuit board that controls all AC functions. Power surges during monsoon storms cause failures.
⚠ Pro needed - diagnostic required ($250-600 repair)
Remove thermostat from wall (most snap off). Find the Y (yellow) and R (red) wires. Carefully touch them together for 2-3 seconds. If outdoor unit starts, thermostat is bad.
⚠️ Caution: Only do this if comfortable with wiring. If unsure, call a pro.
Thermostat
$150-$350
Capacitor
$150-$300
Contactor
$150-$250
Control Board
$250-$600
💰 Most "won't turn on" issues cost $150-300 to fix. Diagnostic fee typically $75-125 (often waived if you proceed with repair).
If DIY troubleshooting didn't work, connect with Las Vegas AC specialists for same-day diagnosis and repair.