Hi DAve:
It sounds like two different problems. I've recently done some work on my Vac system and although it works fine, the vac is under 15, so I'll probably do a rebuild this summer with info I've gotten from this board.
I once had an intermitant problem similar to yours, the ac only blowing hot air. turns out, if I remember right, that the thermal sensor mounted in the middle of the dashboard had come disconnected. This is a pain to get at, but if you pull out the radio you can snake your hand up to touch the bottom of the connector and feel that it is still connected. If you try to just pull it straight up you will probably disconnect it and not know if it ever was connected. This thermistor is required to tell the cabin temp and thereofre could be a source of your problem.
have you ever had the AC charged? I had a retrofit to new collant done to mine last summer and everything works like new.
good luck;
john