No heat warranty service call. Check and find heating system operating normally with worn and weak flame sensor. Need to replace flame sensor. Find thermostat also not holding programs properly and reset itself. Suggest upgrading tstat for better control. Find house have 2 level with open floor plan causing heat to rise upstairs and making upstairs hotter than the lower level. System operating at this time. Give customer estimate to repair flame sensor and upgrade tstat. Customer wants to wait and call us back later. Waive service fee due to warranty call back.