I have a 1996 Ram 1500 and I’m having some sort of a vacuum problem.

There are a couple of issues – first it won’t idle smooth. The idle goes up and down about 500 RPM every few seconds. Also – If you have the A/C on and run the RPM’s up (say leaving a stop light) the air moves from the front A/C vents up to the defroster. When you reach highway speed it will return to the original setting.

I am really a newbie to this truck so I have no idea where to start trying to diagnose this problem. Vacuum lines????
Any advice is appreciated.

 

THERE SHOULD BE A VACUUM TANK UNDER THE HOOD....MAKE SURE ITS PLUGGED IN..THEN FOLLOW THAT HOSE

 

I had an 97 Ram with the same problem with the vents when you accelerated from a stop sign. Mine started right after I put spark plugs and wires on it. Found out that I must have accidently pulled a vaccum line apart trying to reach the distrubitor cap. With yours idling weird I would defenitly check a vaccum leak probably a larger one if it is running weird. I would check around the intake or throttle body area first. You should be able to hear a leak if you listen close enough. Just my .02 cents

 

there is a one way valve on a vacumn line next to the throttle body on passenger side may be bad. dealer cost around 10.00.
jlr25