Customer keeps both systems set to the upper 70s. Units are 2010. Performed full system tuneup and replaced filters. Due to age the system has rust on the filter driers and the inside evaporator coils. Refrigerant levels are slightly low but have a temp split of 18-20°. Instead of investing into any major repairs or letting the system go out, a comfort advisor will come out this Thursday to quote a new system for both.