Over the last two years I have begun hearing buzzing sounds when the furnace kicked on. Initially it was once a month, then more and more frequent until it was every time. In the last two weeks it has started becoming more of a squeeking sound, almost like air in a line type sound. Is this dangerous or harmful to the HVAC system -- could something be wrong that is doing more damage -- or is this just annoying -- the sound doesn't really bother me and I don't want to have someone come out for just a silly sound... thoughts?

You didn`t say if it was gas,electric, or the kind of furnace,, I would pull the cover and see if I could determine maybe where the noise is coming from,, could be wear and tare,, could be more or less,, but you don`t want whatever it is to give out on a cold Saturday night, when you can`t get anyone to come out,, a preventive maintenance check-up,, could save some bigger bucks later