Performed cool home check in heating on both systems. The mini split is operating properly. The main house furnace was giving the 10 flash code again. I examined the condensation system for the furnace and found the furnace had been installed at an extreme angle to help the cooling coil Drain better but was making the condensation drain for the combustion motor go uphill. I re angled the unit and the flue pipe drained further. If the homeowners have this issue again, the 2 inch PVC flue pipe will need to be cut and re-angled to illuminate this issue.