Performed AC cool check on two systems. Checked electrical, mechanical, safety, and performance of the systems. Drain lines were cleared and treated. The blower wheels are clean. Condenser fan motors and capacitors are in good condition. Refrigerant charge within spec on both systems. The attic system that conditions the living room and kitchen area has an electronic safety switch that is failing. The switch is only passing a signal intermittently causing the condenser to stop and start rapidly. No other major issues found. Options for repair were presented to the customer and he chose to have the failing safety switch replaced. Completed repair and function checked the system. Both systems were running at the time of departure.