The HVAC on my FD is not switching the airflow to full dash output when I select this mode. All the other modes (bi-level, floor, floor+windscreen, windscreen) function so it seems like the vent control doors are working.

I have noticed that I can switch from, say, floor to bi level mode and get air from the dash, but if I quickly switch from floor to dash there is no change. This is leading me to believe that the problem is the dash switch. But, I have no experience with FD failure HVAC vent control failure modes. Is the vent control switch a common failure item? Or should I be looking at something else?

I have not had the dash apart yet to troubleshoot, just wanted to try to get some feedback in advance.

 

I have that switch if you want
Pm me

 

Just to close the loop on my original post, I sourced a used HVAC control setup with switches and the circuit board. I swapped out the temp switch unit module and the circuit board into my housing and that solved the problem...I now have fully functioning vent operation. I'm suspecting that the switch was the bad part but since I had a replacement circuit board I swapped that in as well. One or both did the job and it really makes a difference in airflow to have proper dash vent selection!