Make sure the knob on the center air duct is turned to the red and not the blue. At blue, only outside air passes through when you have the heat on. On red, heated air passes through...obviously, half way the air is partly heated.
<span style='color:green'>1994 325i </span>- - - 75,000 mi.
No mods - - - very happy as is!
<span style='color:green'>1995 525i </span>- - - 154,000 mi.
No squeaks or rattles... unreal!