In a medium bowl, whisk together the soup and milk until combined. Then whisk in the ranch dressing mix. Set aside.
To a 5-quart slow cooker, add the frozen potatoes, ranch/soup mixture, chicken, and bacon. Stir to combine.
Cover and cook on HIGH for 4 hours, or until the chicken is fully cooked and the potatoes are tender.
Take the cover off the slow cooker, sprinkle the top with cheddar cheese. Re-cover and cook for another 5-10 minutes, or until the cheese is melted. Serve warm.