Get a big end wrench that will fit on the nut, and hit it with a hammer.
A sharp blow will usually break it loose.
I don't remember the size of the wrench, but I had to go buy
a cheap one at Harbor Freight.
Most parts stores sell a special wrench set just for cooling fan clutches.
Dodge is not the only manufacturer to use this set up, Ford, and chevy
also use it on there late model vehicles w/mechanical cooling fans.
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