Reviewed equipment and found outdoor unit capacitor looked clean and measured proper capacitance. Contactor slightly worn but replacement not required at this time. Found outdoor unit not starting due to no low voltage present to contactor. Inspected furnace and found 6 flash code indicating open rollout. Tested all rollouts and checked air filter. Found no low voltage at R and C on board. Found fuse blown. Inspected thermostat and found common wire (blue) landing on Rc terminal. This caused short and fuse to blow. Removed from Rc terminal (no provisions for comon on thermostat). Replaced fuse and tested ac operation. Unit outdoor coil is dirty and recommend annual service on system.