I have the opposite problem than most of the heating & A/C situations that are listed in the archives. The A/C works fine in our 1987 300e.

However, when the pushbutton unit is set to the automatic mode and the thumbwheel is moved to any heat settings, the center vents close but we get no obvious heat and the A/C compressor remains engaged.

Any guidance re: diagonostic direction would be appreciated.

Thanks,
Bob