Performed maintenance on two systems. Gas furnaces with AC cooling. Upstairs filter is still acceptable. Upstairs system does not operate very much. The downstairs filter will be ready for replacement on next visit 16 x 25 x 5. Please have the technician bring a filter with them if she is not able to find them on her own. Inspected electrical connections and components. Treated condensate drain lines with chlorinating tablets. Cleaned flame. Sensors of gas furnaces. Inspected operations and units currently are functioning properly.