Mom's Chilly-Day Cheese Soup

Combine potatoes, onion and water in a large saucepan. Bring to a boil over medium-high heat. Reduce heat and simmer until tender, 15 to 20 minutes. Add frozen vegetables; cook until tender, about 12 to 15 minutes. Stir in soups; mix well. Add cheese and simmer for a few more minutes, until cheese is melted.