no face vent heat on AUTO

[Russianblue]

for some reason I cannot get air to blow through my face level air vents when my heater is on the AUTO setting. not consistently anyway. if I press the face vent button, the warm air flows immediately. if I press auto, it doesn't.

it doesn't matter if the cold hot wheel is toward hot or cold. if it's on auto, I can roll it all the way up or down....but nothing happens.

but wait...on a completely random basis, but sometimes never, after I drive around for an unspecified time with the IHKA on auto, all a sudden out of nowhere the vent will open and air will start flowing from the face vents. it's as if the vent servo finally just activates itself. but it hardly does this anymore.

any ideas?