does not work: climate fan for vent or heat; a/c won't engage

[hplacecf]

hi.

1979 chevy pickup.
350 engine

just got it and trying to get things going.

the climate fan switch when switched on (any of the speeds) does not work, not does the a/c come on when the slide is set to a/c.

when I start the truck i hear the blower motor come on (I think it runs continuously maybe?), so that works.

I found a fuse on the fuse box and swapped it out with a fuse I know works, but still no good.

the fuse i found was 'b' on the 1980 chart at this link:

http://www.chuckschevytruckpages.com/77fusebox.html

any ideas?

I searched and searched but could not find anything.

thanks in advance