Ok, to start this off, this information is second hand(from Wife). I have absolutely no sense of smell and have been like this all my life. With that being said;
I have had this 2004 TJ unlimited for 2 months. The day I got it home, she opened the door and told me it smelled funny inside. It is my daily driver and I have not noticed anything, In my work vehicle a blown heater core caused me to almost crash because I could not smell it and it built up so bad inside that I started to black out.
With all of that, we went out tonight and it was around 25degrees so the heater was necessary. Once again, minor smell when she got into the car but when I turned on the heater after it warmed up she said the smell was so bad she was thinking of rolling down the windows.
Can a bad heater core cause a residual smell in the cab and get worse with the heater running? I think it is bad I am just trying to sort out the 2 differences. If bad, how hard to replace?