I had this problem about 3 years ago. It turned out to be the cable holder broke loose on the middle slide control (outside air diverter) so that when I tried to close off the outside air the cable moved but didn't close the flap. Access to the flap area is through the right side of the glove box area. You will see the cable where it attachs to the flap in ductwork. When you move the middle slider look to see if the flap control lever moves. Mine did not as the cable flexed around because the holder for the cable broke. So I just reached in and held the cable firm, moved the slide lever and watched the lever to the flap close. Instant heat. I could have bought a new flap unit or fabricated a new holder, but I just open and close the flap this way according to the season. Check it out.

Jim
1983 533i

on a cold(15-30F) morning? 'Cause mine sure does seem to take forever. Any ideas if this is a problem--or if this is just normal. Thanks.

Mike