Ok the bobcat strikes again. Has anyone had their pattern changer seize up on them? One of my operators runs the opposite pattern from me and we have noticed the valve getting stiffer recently till not it is seized tight will not move. Looking at the machine it appears that most of the cab has to come out including the ac or am I missing something?
Try slipping the box end of a wrench over the 'L' shaped rod that threads into the shaft and using the extra leverage that it provides you. I've had a few in 430's that see lots of salt get really sticky, a 7/16" tends to work best in my travels. If the valve is completely seized, than yes, all the dash paneling, seat and base have to come out. If you remove enough of the floorplates the HVAC unit can be coerced to give some extra room without removing any refrigerant.
Update finally had a rain day and pulled the machine into the shop. After disassembly of the valve a small amount of rust was in it that had seized it up polished everything new O-rings and she is back to work.