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

Most ACs won’t start due to a tripped breaker, dead thermostat batteries, a full condensate drain safety switch, or a failed part like a capacitor or contactor. Try these quick checks first.

• Replace thermostat batteries and confirm “Cool” and fan “Auto.”
• Reset the HVAC breaker at the main panel.
• Change a clogged filter.
• Check the outdoor disconnect and ensure the furnace/air handler door is latched. If it still won’t start, we can diagnose and repair in the Phoenix area. Weekday diagnostic is $55; weekend is $89. The fee is waived if we complete a repair at the visit. <br/>

Updated: 2025-12-03 00:00:00 <br/> Need help in Maricopa Colony, AZ? Call (602) 793-2477 or book online.