iirc the '97 is designed for R134.
That was my understanding, if so it might increase the efficiency for those mid summer days.
update:
regarding the spare tire carrier, I got the new spare tire and wheel this Saturday. After lengthening the bolts 2", tried to install the spare. The spare is 1/2" too wide to clear the receiver hitch and pushed tight against the back receiver hitch, there is about a 1/2" clearance between the tire and the axle.
So this spring, I will weld up a new receiver hitch and trying to come up with a better spare tire carrier.