Performed diagnostic on 3 year old unit. Homeowner states System isn’t cooling. Outdoor unit does not turn on. Cycled system for cooling. Outdoor unit is not turning over. Checked system electrical. No line voltage coming to unit. Found breaker in the off position. Turned breaker on and system came on and started cooling. Refrigerant pressures are ok, weather not fully ideal for refrigerant check but system is cooling. Signed homeowner up on monthly maintenance program. System is operational upon departure.