[AllanP]

I found a disconnected vacum line going into the firewall right behind the engines valve cover. Anyone know what its for?
I replaced it but notice nothing different.

Thanks.

 

[BigBlue]

It goes to your 4wd actuator on your axle.

 

[kench0224v]

it also controls the ducts on your ac. if you disconnect it, it will get stuck in whatever position you left it in. and it also controls your 4x4

 

[Mopar1973Man]

Yeap... The vacuum line controls all your vents inside... But for safety measure it should default to DEF mode... As for the 4WD that is if you have a CAD system.. My 2002 doesn't have this but my Mom's truck does...