Something else which might be fitable to the Vanagon for better A/C performance.

http://www.procooler.com/

The  Pro Cooler actually replaces the factory installed receiver/dryer in your Porsche 911. It will dramatically improve the performance of your Porsche 911 air conditioning system. It looks like a combination of a receiver/dryer and an accumulator into a single device. By placing the receiver/dryer inside a refrigerant accumulator, the normally hot receiver is cooled by the expanding refrigerant in the accumulator on its way back to the compressor. By super-cooling the refrigerant in the receiver, The Pro Cooler reduces the operating pressure in the high-pressure loop of the system. This reduction in head pressure reduces the energy required to operate the system. The result is cold a/c in your Porsche 911, a wonderful thing.

  The heat absorbed by the cooling refrigerant in the accumulator side of The Pro Cooler insures that any remaining liquid refrigerant that could damage the compressor is turned to gas before reaching the compressor. The Pro Cooler's clever recycling of the excess energy potential found in the 911 air conditioning systems, or any automobile air conditioning, improves the cooling capacity and energy efficiency considerably. Not only for Porsche 911 air conditioning but for any automobile or commercial air conditioning system.