Thanks guys for your insight. However, knowing that six months ago the original problem began as not getting any heat underneath, but getting lots of heat out of the defrost vents has me stumped. I suppose this could be multiple problems, but in your opinion, is it possible that the control head unit (whatever the push button device is behind the dash) could also be faulty?

any way to check the functioning of the blower motor with external power?

Have you seen a post that shows how to extract this unit? I haven't found one yet.

thanks again.