Not exactly sure where to post this so I will start here. I have some mouse damage. I got the electrical all repaired now. I have the vacuum line diagram for the engine and emissions. My problem is I have 2 (Hard Plastic) lines from the firewall from the HAVAC wire harness one line is short with a rubber elbow which I believe goes to the vacuum source with the check valve from the engine. I don't know where the longer line with the straight rubber connector end goes. The HVAC diagram only shows it going to the rubber grommet and calls it dash.

1989 Trans Am
305 TBI
Automatic
A/C

Thanks in advance

 

the short one does connect to a source of manifold vacuum as you suspect . The long one connects to the heater control valve , which is the black plastic valve on the passenger's side , right in the area between the engine and the radiator overflow tank .

Here's a picture of the valve . The vacuum line connects to the top ......

 

Thank you so very much, this mystery has been solved. Happy Thanksgiving.

Rick