I have a 2001 Dodge 1500 5.2L 4 x 4. I'm the original owner and the truck has 161,000 miles. I started having issues about two years ago getting my truck into 4W drive. I would take about 1/4 of mile to get to lock it in. So I installed a new Dorman vacuum actuator amount 8 months ago and it worked for a while and it then totally failed.

I installed a 2nd Dorman actuator pump last month due to the Advance Auto parts warranty. Now it takes about 1 to 2 miles for it will lock in and about 1 mile to get it out of gear.

I replaced most of the vacuum lines amount 18 months and I don't notice any cracks.

Here lately I've noticed a 2nd issue. When I am going up a hill or just hitting the gas a little extra. The fan automatically switches from pushing air out the vents facing me, to pushing air out the vents by the windshield instead. Then, as soon as I let off the gas, cold air returns to the vents facing me.

So I know I have some type of vacuum leak and don't know where to start. I read something about vacuum reservoir?

Any help would be much appreciated.

Shane

 

There is a vacuum reservoir under the cowl at the base of the windshield. They seldom fail though.

Did you check the steel lines running along the frame for the CAD? They like to rust out.

Does your cruise control work right? The line under the battery can sometimes get destroyed by stuff dripping off the battery.......

 

It sounds like you have a vacuum leak and need to remedy that but, the posi-lok system would take care of any "iffy" issues with your CAD.

 

I replacement all my steel lines last year and they look okay now. No issues with the cruise control.

 

Then I would start with the vacuum check valves at the intake manifold. Also, make sure all the lines to and from the t-case are clear. Especially the green vent line.

 

While it may be true that the vacuum reservoir under the cowl is fairly robust it can crack and cause the symptoms you're seeing. Happened to my 97 Ram.

 

It could be the vacuum thingy on the transfer case. Sorry, can't remember it's proper name. Look for a place that has a smoke machine. The smoke shoots out of the vacuum leak, making it easy to see.