Johnson, did you read my response to your original question?
Leave it alone, unless something is wrong with it. The expansion valve is the least likely piece of an A/C system that will improve efficiency. Get a bigger condenser or a higher capacity compressor if you are bound and determined to spend money on this project.
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.