Abstract: An air conditioning drain cleaning system with an automated blow-out cycle to clean out an evaporator pan drain pipe. The system has a pneumatic valve assembly, a controller, a float level switch assembly and a plurality of air lines in a manifold for actuating the pneumatic valve assembly and blowing out the drain pipe. The controller directs the system to initiate or repeat a blow-out cycle until the drain pipe is clear. The pneumatic valve assembly bisects the drain pipe to selectively close the pipe for cleaning with a pair of high pressure air shots, one shot toward each pipe end to dislodge a clog. The float level switch assembly signals the controller if the condensate level in the drain pan drops. If the condensate level does not drop, the controller initiates a further blow-out cycle at increased pressures until the line is clear.