Goodman furnace repair ,when I arrival there was no issues immediately , I recommended to have a furnace maintenance . During testing of the furnace after clean , the furnace failed due to the high heat limit opening . I discussed with the customer the merv 12 filter they are using is not allowing enough air flow , and recommend a merv 8 or pure air x filter system . I also have opening a damper in the basement on the return side and adjusted fan speed to the next setting from 400 cfm to 650 on first stage . I also verified all duct work is open and free of blockages . Furnace is operating well .