I was driving my truck home from having a small leak in the A/C system fixed. Now it blows nice and cold - but only sometimes out the dash vents, more often out the defroster vent. Moving the controls doesn't seem to make a difference in what it does, except that setting the fan on high does seem to force it out the defroster more.

Is the infamous blend door problem? If so, am I going to have to pull the entire fricking dash out?