Does the Dina have an air intake plenum like the GMC's? or does the intake go through a pipe directly to the filters? If there is a plenum, it would behoove you to clean it out.
When I did my GM, I pulled mouse houses, crud, dust, more crud, dried mud, etc out.
I also removed the air intake to blower housing and cleaned that screen out. It was amazing the things that had gotten in it over the years. There was even a whole moth, of unknown origin, well preserved with Delo's finest.
Brian if I remember correctly Bobby used a jigsaw and cut the side of the intake open so he could get in there and clean it then he used a strip of tin and pop rivets to close it back up and also riveted the wire mesh stuff in also (I'm not familar with the term hardware screen I guess it's the same as what Bobby used) and as far as I know he hasn't had anymore problems with it.
Does this mean he removed the bars across the air intake on the outside of the bus? How did he get the crud out? With a vacuum maybe as the screen in the intake is well below the top of the bus?
I'm wondering if there isn't a better way if I'm removing the bathroom and stripping the bus anyhow. I'll have to check the manuals.