I turned on my windscreen defroster yesterday while stopped at red light and my car didn't seem to like it; it rumbled for a moment, but then seemed to be okay, however a few minutes later as I was pulling into my home I noticed a bad smell coming through the vents and when I parked I saw that there was smoke emanating from under my hood. Unfortunately I have not had a chance to check under the hood due to weather, but the issue only happens when the defroster is activated (not for the rear window tho) and regardless of what the temperature is set to, and not when the air is turned on or the heat is turned up (basically it just happens when one of the two front window defroster buttons are selected, the ones that light up orange and not green on the air control panel). I was hoping someone might have an idea of what's going wrong and how to fix it, or maybe pointers on what to look for when I do have an opportunity to pop the hood. Thanks in advance!

Edit: 2010 Civic LX