I've got no heat in my suburban, tore it apart and found broken hinge/actuator on blend door. Stuck a piece of wood in there keeping it open, thought I'd have heat all the time......NOT. Need to check hoses, heater core etc. Not looking forward to it and I don't envy you. I'd rather pull a motor!
When I turn on the heat in my daily driver, the windshield fogs up....