1997 Chevy Tahoe water pump replacement

I started removing the fan assembly and ran into a major problem. There is a "spacer" nut between the fan and the pump pulley. I have to remove this to gain access to the water pump. I have a repair manual that says a large adjustable wrench will work, but I have no idea which way to turn the wrench to break this loose. I have tried turning it both ways but this did not work. Both the fan assembly and the pump pulley housing turn freely and I am at a loss as to what to do next. Thanks for your help