AC Refridgerant What AC refridgerant do I need to recharge my 1995 Nissan Quest Minivan 3.0L 6-cyl? If it is R-14, am I able to convert to 134A?

I believe you meant R-12. In a 1995 year vehicle, you do not need R-12. You will need to charge with R-134a refrigerant. If you don't have the proper equipment to recover any refrigerant that is left in the system, I would recommend you take your vehicle to a garage only for the simple reason that if you can't recover the system, you don't know how much refrigerant is already in the system and so you don't know how much to put it to fill the system- and yes, you can overfill it and cause a whole other issue, which will usually result in poor cooling and also run the risk of damaging system components. Even if you know without a doubt that the system is completely empty- such as you had it apart to replace a component- you should evacutate the system for a minimum of 30 minutes to remove any moisture in the system. Moisture reacts with the refrigerant and if trapped in the system, can eat hoses, etc from the inside-out.