I just bought one of those one-way vacuum valves to stop my A/C from switching from the top vents to the defroster when accelerating.

Can someone tell me exactly where in the vacuum system I need to insert this thing? It didn't come with instructions.

 

The HVAC vacuum line comes off the intake on the passenger side. The valve should be only inches away from the intake in this vacuum line. You'll also want to install it so that the airflows through the valve towards the intake.

 

Thanks brother. I have just about everything in this rig fixed now -- so this last vacuum issue really torques me every time I move away from stop sign or traffic signal. It's a small thing but it annoys the heck out of me; that all ends today.

 

It ends today IF the valve is the problem. You could still have a vacuum leak in that line that you haven't yet discovered.