I had an air combustion problem in the beginning of the year. I found that my OAK was clogged. This caused a very dirty burn which resulted in my vinyl siding around my exhaust cap to become black. This is a large area. Around 50 sq. ft. Anyone out there have a cleaning solution. Vinyl Siding cleaner from HD didn't do much, neither did the pressure washer. Help. The wife grows angry every time she pulls the car in the driveway.