Painting - cracks in paint

I'm removing wallpaper and plan to paint the walls in my living room. The wallpaper came off OK, but I don't like what I've found on one wall. The paint (I think it's paint-it's off white in color) is not adhered to the wall properly. There are lots of small cracks and peeling on approximately 50% of the wall. I can remove most of the peeling with a scraper, but I am concerned that what's left won't provide a good base for the new paint. I could sand the entire wall, but I dread the thought of the dust that would raise.

By the way, the house is about 20 years old and this is an exterior wall. I planned to use Zinsser 1-2-3 primer before painting.

Thanks!

Peter

I'd sand the wall, you can use a hand sander that attaches to a shop vac. These are available at most hardware stores. It virtually eliminates 95% of the dust. Then prime it with a coat of Zinsser's Gardz. That will seal it down better than 123, and provide a better surface for patching the peeled areas.

And what I mean by sanding, you don't have to sand it all off, just scrape every that will come off, lightly sand the surface, and use Gardz to lock down what you couldn't scrape off.