Here is background. I found condensation issues on roof, has mold, is getting replaced. I have high efficiency miller gas furnace which is also getting replaced, going to 80%, it has been leaking water from heat exchanger casing, only when on, was told it is bearings. It has corrosion spot in other area from casing, where it looks like was also leaking water. Again it seems like it happens when it’s on. It is ten years old. Posting Pictures aren’t working for me, btw.

So I sealed the furnace closet, (shut off breaker and all that) with newspaper afraid of mold, etc. since roofers coming in a few weeks. So I noticed when it was windy the newspaper was moving in and out, I also took out ceiling fan and it has bag around remaining parts and is sealed and it was also puffing from wind.

Today I did laundry and when running dryer ( nothing blocked, checked, not too hot, etc) the ceiling fan bag and furnace paper were popped out like they wanted to blow. My furnace exhausts out roof and condenses underneath into ground, my dryer goes from underneath to outside through skirting, short distance, it has new cover flapper type. This is a mobile home. Why all the air?

I want to figure this out before I get new furnace and roof. Was wondering if I had attic pressure issues, air leak furnace, was the h.e. furnace too much or set to high pressure wise for mobile home, redid mobile home years ago like a house, is it too tight, this whole thing started in august with a smell and here I am.
Seems odd something exhausting outside (dryer) is affecting roof so greatly air wise? And that furnace should be windy?

Thank you to anyone for any help and all of your patience, I am at a loss.