I've been having some issue with the front windshield fogging up when I turned on the defroster. After doing some searching on here I narrowed it down to a heater core going bad. Took it to a trusted mechanic because I don't have the patient or the time to try and replace the heater core myself due to how extensive it is on the wj. My mechanic told me I was better off selling and looking into something new because it wasn't worth the bill. I'd rather not pick up a car payment since I'm trying to save for a house so I took a chance and spent $20 at autozone on a radiator repair and so far things are getting better. If anyone is having the same issue I know there are a few threads of people looking for options so I wanted to put it out there that depending on how bad your problem may be this fix may just help out. Just make sure you turn the heater on when running the product through the radiator so it cycles through the heater core!!