Did a no heat diagnostic. Found blown fuse. Troubleshoot control board and in heat mode fuse pops. Found a charred control board.zone board doesn’t have individual power source and is powered by control board.system has Dirty blower wheel.no Te flood protection. Out of tolerance indoor and out door capacitor. Dirty condenser coil. Will need to rewire system and install transformer for zone board. Customer signed for bandage repair need to order control board for repair. Knett0527@yahoo.com