Last year my wife and I made a mistake. We left a bottle of Bull Frog sunscreen in our Jeep after winter began. When entered the Jeep one morning to find that the can had emptied itself into the Jeep. This caused all of the windows to be covered by the oily liquid, that we did not get rid of until summer, the winters in Fairbanks are 7 months long. Now that it is getting cold again, we are having the same problem again, but now it is coming out of the defrost and causing the windshield to fog up when it is on defrost. There also is smoke of some sort coming out of the vents. I am not sure if replacing the heater core will do. Any suggestions? Is there a filter that I am missing?