A fresh AC charge with a pack of dye could be had for $150 from
a good mechanic while evaporator service would be at least $1000.
Our 95 AC was weak and I had it recharged. A year later it is
still blowing cold. So, I'd first try a recharge. If it leaks
down quickly you have bigger problems but the dye will help to
pinpoint the leak. In fact, I would suspect a service shop would
first want to charge it and add dye to help locate any leaks (so
it is a good place to start).

The shift lock solenoid is a known trouble-maker and that is probably
the problem with the shift lock. You can look through the problem
descriptions for transmissions at: http://volvospeed.com/bay13.htm
at see if any of them more closely match your problems.