88 suburban a/c problem

[ThreeQuarter]

I shoulda added this on the first post: If one setting did blow noticeably harder than the other, then maybe one of your dampers wasn't opening fully, and it restricted airflow, or there's a something blocking the airway (plastic grocery bag, etc.).

I haven't had one of those model trucks in a long time, so I can't remember if the MAX/NORM difference was as noticeable as the 88-98 pickups I've had...maybe on those models the sound doesn't change much

It could be that a damper door isn't moving to give you the higher/lower rate of airflow you're remembering. Can you hear damper doors closing when you switch back and forth?