Once you said some spots looked brown.... listen to Brian...
Have you seen the FSM manual for that rats nest of vacuum and electrical interactivity ?
Just for what you are dealing with at the dash controls...not shared stuff like the evap or blower... just the dash stuff.... I quit counting at 125 pages... and like the other manuals it was translated by a non English as first language person...
Be sure all your vacuum system is in good shape, buy a rebuilt CCU from someone trusted.. THEN attempt to get it all working together...