if your windshield fogs up easy on the drivers side, than your heater core or the o-rings on the piping to the heater core are shot. This is probably the stupidest fix i've done. Really annoying and time consuming, but you should be able to get it done if your hands grow from the right spots.
1990 M5 Euro
You wash your car like it was your firstborn child, you tend to its needs like it was your own body, you protect it like it's your family, then you drive it like you stole it