The blower motor resistor on a 1991 Dodge Dynasty is typically located
behind the glove box. To access it, you'll likely need to remove the glove box itself. However, the exact location might vary slightly depending on the specific trim level. It's usually attached to the blower motor housing or nearby.
Before you start, it's a good idea to consult a repair manual specific to your 1991 Dodge Dynasty. A Haynes or Chilton manual will have diagrams and detailed instructions to help you locate the resistor and safely replace it.