Performed heating maintenance. Visual inspection of electrical (good) no burnt or overheated wire connections, Control board / solder joints good. blower motor good, Tested amp draws (good), Flame sensor reading 2.6 (good) Burners clean, Heater safeties good, Gas pressure 3.49 good, ohms reading of hot surface igniter 62.8, washed air filters. fresh air draft motor inspected found problem with vibrating / making noise Recommend replacement of motor assembly while unit is possibly under manufactures warranty. Customer indicated noise happens frequently with the motor assembly. Will check part availability and unit warranty information. Will give customer a call with price and availability and information discovered on warranty. Reinstalled set up navilink system for tankless hot water heater.