Not real sure just what you are saying as to what pan? The copper pipes that go to the evap plates where the ice is made are supposed to frost over. They get colder than dew point of the air so this is normal. But all the pipes should frost. Does the unit shut down and give any type of beeping noises? This would be the control giving you a trouble code. You may have a water valve leaking. Turn unit off and see if water continues to run. All water should stop within a few seconds. Let me know what you find. Please verify model and serial numbers.