Depending on the brand, you can probably just get a motor kit from a truck stop, or walmart for the fridge you have. It is a very inexpensive way of bringing the fridge back to new
If you do buy a new one that is 12 volt, I would suggest checking out Walmart. They carry a Coleman model, that is only a fridge. It doesn't heat and cool, it only cools.This is what I have now, and unlike all the others I have bought, this one hasn't froze up on me yet, and hasn't gotten noisy like all the others tend to do.