Why Is My Air Conditioner Not Turning On Despite Thermostat Set to Cool?

An air conditioner not turning on with the thermostat set to Cool usually points to a power, control, or safety shutoff issue rather than the setting itself. The most common cause is a tripped breaker or blown fuse, followed by dead thermostat batteries. A clogged condensate drain can trigger a float switch that stops the system, and failed start parts like a capacitor or contactor can prevent the outdoor unit from starting. One quick tech clue: if both the indoor blower and outdoor fan stay silent with no click, suspect an upstream power cutoff first. We handle this problem often for homeowners around Goodyear and nearby suburbs. If basic checks don’t restore operation, it likely needs professional diagnostics, and we do offer 24/7 emergency service.

Try these safe checks before you call:

• Set thermostat to Cool, lower 5°F, and replace the thermostat batteries.
• Confirm the furnace/air-handler switch is ON and the door panel is fully seated.
• Check the AC breaker; if tripped, switch fully OFF, wait 60 seconds, then ON once.
• Look for water in the drain pan, replace a clogged filter, and let any iced coil thaw.

Turn off power at the breaker before inspecting panels or wiring.

Updated: 2026-06-18

Need help in Goodyear, AZ? Call (623) 853-1482 or book online.