Does your air conditioner work? These systems are designed for the A/C compressor to run when the system is in Defrost mode in order to dehumidify the air. If the A/C isn't working, you won't get the best performance from the defroster. This will be especially true in a wet climate, such as where you are in Oregon.there is a problem with the defroster, seems every time I turn the heater on it fogs up the windows, the longer it runs the worse it gets. it is not the heater core,