Air conditioning

You have to push the button "a/c" turn turn it on, I assume that when asked if MAN appear to left of A/C control you mean manual. There is not a place to for a MAN to appear or flash

Yes, air blows in heat mode, all modes operate, when control is turned to split air between floor and dash vents with a/c on air is blowing on driver and passenger side, but not cold?

Yes system was charged and new schrader valves put two months ago, just to be clear- there is three vents in center of dash above radio, the farthest right and the one against passenger door are the only two blowing "cold " air

NO AUTO and DUAL-ZONE buttons

Have your ac presures checked again you most likely have a small leak most likely at the compressor or the evaporator core

I had a radio installed buy professional during winter, the a/c was working and abrubtly stopped blowing cold air at the end of last summer I waited through winter and this past march had intake manifold gasket replaced at a reputable service station, I also had them check a/c and was told there was no freon in system do to bad schrader valve so they replaced valves and recharged system and that when I noticed it blowing cold out of two right dash vents only. Thank for all your suggestions by the way