Performed Cool Home heating maintenance on Carrier gas furnace. Did find flame sensor having intermitting problem. Cleaned sensor off. Furnace began to operate properly. Informed homeowner of flame sensor and advised him that it’s not something to be urgent about being that system is operating at the moment and homeowners don’t use furnace much but still maybe a potential issue we may need to address in the future is problem duplicates. System is operating properly In heat at time of departure