Up on arrival performed heating annual maintenance on 01/02/2020. Checked all thermostat for operation, checked all systems for operation. Took delta T readings. Checked all electrical components. Changed all air filter and belts. Found system number 4 carrier M#48TCED14A3A6 serial # 5012G20114. Was not running. Disconnect is was set on off position thermostat wires was disconnected. I was instructed to not touch that RTU . All other systems operating normal at this time .