Came out to call to give estimate. Customer wanted a diagnostic of the system to see what was wrong with it and if it can be repaired or if it needs to be replaced. Customer is going through his insurance to fix or replace the system. Checked system over and found batteries dead in thermostat. After I replaced the customer supplied batteries I went to the system to diagnose it. Found system getting proper power supply through the transformer but nothing operating through the control board. At this moment the control board needs to be replaced before I can go any further with the system. The furnace and ac will not operate without the control board. Told customer I could look into getting the control board, but may not be able to locate one. There’s no telling what else could be wrong with the system. Unit should be replaced due to age, condition and being inoperable.