FWIW, I was having the same 2min flashing pblm on my 93. The cause was from my self-change over of the AC system to R134a.
What I was having to do is wait for the display to stop blinking, run the temp down to 60, wait about 1 minute and then run the temp up to 70. This would cause the damper door to properly adjust to a heat position.
However, the other day I got lucky. I had yet to try the diag steps listed above, but found that taking the temp down to 60, waiting 2 minutes and then shutting down the car, the system reset itself. Please note, I stumbled across this, but it did work