Originally Posted by gettawaydriver
So we made our first outing of the year with our pup and were very excited for another season despite the forecasted cool wet weather. As it was so cold we had to run the furnace and it was all fine and good the first evening, night, and morning. However the afternoon of the second day it started to make unusual noises.
As the fan was running it would change tone almost like it was under increasing load, only for a few seconds, then back to its original running noise. It would do this four or five times a minute. I turned off all other power draws and swapped the battery for a freshly charged one. No improvement.
Anyone experience this before or have any ideas?
My guess is the "rotor" containing the vent fan and combustion air fan is running too far down stream and rubbing. When it rubs it slows down and the forces causing it to go down stream are lessened therefore runs in the middle again. A repeating problem without a self cure. Best thing is get it changed out, the entire furnace, or if you're handy take it apart and repair the cause of the shaft looseness. Believe Suburban has a two year warranty on the heater, don't let it go.