I have the maintenance manual for the MC9 for years 1989 (electronic copy) and 1992 (hard copy). I suspect MCI put out a revised maintenance book in 1995 or later covering R134a as I see the MC9 lists two different compressors. The older manuals cover R12 but I was hoping someone might have a later manual, specifically section 16. If you don't have the entire section 16 then the parts on the pressure and temperatures readings for the superheat adjustment would be a huge help. I personally would prefer taking it to a shop but my church doesn't have the money at the moment so I'm trying to narrow down what might be the issue and make quick inexpensive fixes before biting the bullet.
Another twig in the soup ... my '96 MC12 was running 22 if I remember correctly.