Combine the chicken, potatoes, carrots, celery, chicken soup, chicken bouillon, garlic salt, celery salt, and black pepper in a slow cooker; cook on High for 5 hours.
Stir the frozen mixed vegetables into the slow cooker, and cook 1 hour more.
Combine the chicken, potatoes, carrots, celery, chicken soup, chicken bouillon, garlic salt, celery salt, and black pepper in a slow cooker; cook on High for 5 hours.
Stir the frozen mixed vegetables into the slow cooker, and cook 1 hour more.
Notes: I haven't actually tried this yet, but it looks like it'll be amazing.