Performed annual heating maintenance of a split heat pump Roseville. Turned on system, system working at this time. Cleaned return air filter grill and changed filter. Washed outside heat pump coils see before and after pictures. Went into attic to look at air handler and noticed a few things. The primary drain runs up hill. And the return flex duct is grey and falling apart. Then I went thru and inspected the rest of the house duct work, it’s in just as bad shape. All other parts in specs at this time. Due to condition of duct work, recommend replace over repair.