Check your fan clutch. Engine off (posted for liability sake
) grab the fan and see if it wobbles any, if it does...your fan clutch is bad.
If it is, its not cooling it sufficiently at idle and not pulling enough air across the a/c condenser to make it operate correctly.
If that is indeed the problem, make sure you get a fan clutch from Dodge. If you get a parts store clutch, it'll spin all the time and kill your power/mileage and make your truck sound like a prop plane.
As far as the blower motor/fan...it could either be the relay for the switch or the blower motor itself. I believe they're pretty cheap and not too bad to replace.