AC precision tune up. Clean and tune up AC; cleaned condenser coil, checked all outdoor electrical components, tested indoor air flow, checked refrigerant levels, and tested overall AC operation. Unit did not stay running for long. Unit was giving a error code #53 code after 3 minutes of run time. Outdoor temperature sensor error. Ohmed out sensor, sensor is within range. The plug that goes into control board on A/C is black and the pins on board are black and corroded. Manufacture of A/C said that control board and outdoor temperature sensor and thermistor would have to be replaced. Unit will not work very well this summer due to it not wanting to stay running. Also found the pipe insulation and starter worn out on outside unit. Due to age and condition of system, replacement is recommended over repair. Will have Chris come out tomorrow afternoon to do a A/C estimate. Air Exchanger cleaning and tune up. Remove filters and core to vacuum. Also clean cabinet interior. Inspect bearings