issue Weird noise from heater fan

[Escalade1979]

So today when I was leaving work I noticed that my fan on my heater was extremely loud.....I know normally it is loud when on full blast but this sounded like I had a generator running...It felt like the whole truck was shaking...It only did it on the highest fan setting and one down from the highest...and also did it in both heat and air....It did it through the entire drive home....There was a crap load of snow here today in Ontario...It has since stopped once I tried again after I shovelled my driveway....

 

Any thoughts on what it may have been?

 

Cheers

[tvalley]

So today when I was leaving work I noticed that my fan on my heater was extremely loud.....I know normally it is loud when on full blast but this sounded like I had a generator running...It felt like the whole truck was shaking...It only did it on the highest fan setting and one down from the highest...and also did it in both heat and air....It did it through the entire drive home....There was a crap load of snow here today in Ontario...It has since stopped once I tried again after I shovelled my driveway....

 

Any thoughts on what it may have been?

 

Cheers

I had the exact same thing happen here this morning. It sounds like a jet airplane getting ready to take off in the 2 highest settings. There is a lot of snow here in Mich. also but I don't know what that would have to do with it. I'll check later to see if it's still doing it. I have to visit the dealer next week on another issue so I'll add this to my troubles.