Defroster not working properly

The inside of my windshield fogs up in the morning and when it rains or is humid out. When I run the defrost it clears the inside but forms water on the outside of the windshield down near the cowl. As soon as I turn it off the fog on the inside comes back. It also looks like moisture or vapor is streaming up on the outside when I run the defrost. It is a vicious cycle and makes it hard to see out the windshield. I checked the heater core for leaks and found none. I also checked the A/C charge and found it to be about 40 lb. It is draining out the hose freely also. I don't really know what this could be from. I don't know if I need to increase the temp of the defrost or not. Any input as always would be greatly appreciated. Thank you for your help.