Performed A/C tune-up on a Carrier straight cool system. Checked the electrical, mechanical and performance systems of the unit. Replaced the return air filter. Cleared, cleaned, flushed and treated the drain line. Cleaned the exterior of the furnace and washed the outdoor coil. I replaced the high voltage wire nuts with a Wago wire connector. I found that the thermostat screen is fading and is hard to read. I presented repair options to the homeowner. No other issues were found. The system is operational at this time.