Do I need to turn off AC to clean a drain line?

Yes, you should always turn off your air conditioning system at both the thermostat and the main circuit breaker before attempting to clean or service the condensate drain line. Shutting off the power is a critical safety precaution that protects you from electrical shock, especially since you will often be working around standing water, wet tools, and high-voltage components inside the indoor air handler or near electrical terminals. Additionally, turning off the system prevents the powerful blower fan from running while you are trying to flush or vacuum the lines; if the blower remains active, it creates negative or positive air pressure within the cabinet that can pull cleaning solutions in the wrong direction, spray dirty water into your face, or disrupt the suction of a wet-dry vacuum trying to clear an outdoor clog. Always wait until the cleaning is fully complete before turning the power back on.