Place the chicken, peppers strips and onion in the crockpot.
In a bowl mix the brown sugar and cornstarch. Add 1 cup of the reserved pineapple juice, vinegar, water, soy sauce and salt, blend until smooth. Pour over chicken and veggies.
Cover and cook on LOW for 7 to 9 hours. One hour before serving, add the pineapple chunks, stir into the meat and sauce.