First question is, if you start up with the ac off/ button pressed, turn the ignition to II ( and no engine) how long does the book symbol take to come on, if at all...If no symbol then prob blend motors are ok...engine on now, set to Lo, ac switch unlit (ie on), do you the book symbol after a short time? If no, is the ac clutch spinning, if no then use a spanner to wack the clutch plate...was it magnetised, does it now engage? If yes ( for book symbol) then problem likely lies with ac but then there are several options as to what...remove the circular connector and put a good 9v batt across the terminals does the clutch engage this way ? Let ac run engaged does the system go cold? If not then your ac is probably empty... When was your last re-gas? If recent then poss you have a leak from somewhere...use a UV light and see if you can spot any obv fluorescence...I cd go on for a while, but that's a start