Was wondering if anyone had photos or diagram showing where the vacumn line attaches to "93" 5.2 V8 for the AC/Heat vent selector control. I think I've narrowed down where it enters the cab, (driver side). Vent is in the defrost
setting at all settings. No hissing air detected in cab from tube being disconnected from selector. Seems like a common problem with Dakotas.

 

Did you have vacuum on the line under the hood that is for the blower system? There are vacuum diagrams within the service manual which can be downloaded from the FAQ in this section.

 

I should make sure I identified the the correct vacuum hose first. Here is a photo with an arrow indicating what I think is the line in question.

 

Actually by memory it is on the other side of the brake booster. See green arrow.

 

I can confirm... better late than never, right? If you can follow the port off the passenger side of the intake manifold, it should go approximately where Crazy has indicated. You should be able to see the thin emissions hosing teeing off the various vacuum lines on the passenger side, and follow it back over there on the firewall. Should have a check valve in that line. If it doesn't have a check valve or your check valve is in the wrong direction, you could have problems.