Drain juice from clams into a large skillet with the onion, celery, potatoes and carrots. Add enough water to cover, and cook over medium heat until tender. In a large heavy saucepan, melt butter over medium heat. Whisk in flour until smooth. Whisk in cream and stir constantly until thick and smooth. Stir in vegetables and clam juice. Heat through, but do not boil. Stir in clams just before serving, to avoid making them tough. Once the clams are heated through, stir in vinegar.