same old problem--no heat

[Libby]

Got it. I don't get under the dash very often, obviously. Any thoughts on whether the problem could be the heat valve control switch ? (I'm dangerous when I've got a parts catalog in my hands! )
I just took my beast on some errands, after putting cardboard in front of the rad.; didn't help. I'm going to have to get back to the mechanic next week, but I want to go with all the info I can get.
(BTW, I'm a Cubs fan from birth)