Ivan, the alternator and idler pully are on the passenger side of the engine. If you are sure of the location, it can only be one or the other of these. I would bet on the idler pulley,,

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.