Upon arrival spoke with customer and she explained the outdoor was covered in ice. Filter is clean and new stat is set correctly and working. Went to basement to indoor unit. Wires are all tight and getting correct calls. Blower and coil is clean. Coil showing no signs of leak. Heat strips working properly. Unit is level and duct work is tight. Drain is clear at this time. Went outside and started checking over system. Contacter and capacitor checked within specs. Fan and compressor amped within specs. Refrigerant levels checked within specs. Found defrost board and sensor have failed and is not allowing system to defrost. Called and found system warranty ran out January 2023. Got price and availability for customer, and priced it up with a membership. Customer approved repairs with membership. 11-17-23 Upon arrival spoke with customer and started on outdoor unit. Shut power off pulled board and put new in place. Pulled sensor and out new in place. Put power back on and went inside