Hi. I have a 1999 dodge ram van 1500, and I am learning to do my own repairs. I recently replaced the blower motor and blower switch with this forum's assistance, and now it blows fine but only through the defrost and lower vents. I am guessing maybe I knocked a vacuum line loose while installing things but I can't find any loose hoses or hear anything hissing.

I found this diagram:

but I can't find #5 at all. See how it loops around under the blower motor? I got nothing, as you can see from this pic I took from under the van looking up at the blower:


And the rest if the lines, I think they are in the dash? How do I get to those?

And since I can't hear any hissing, could it be something else? Actuator? Stuck door?

Any guidance would be appreciated. Thanks!

 

Do the vents switch at all when you try and adjust them? Do you hear any of the doors moving? If nothing seems to work, look under the hood for where the controls get their source vacuum from. The plastic lines are notorious for getting brittle with age, and a harsh look will break them.

 

When I turn the dial to switch vents, I don't hear any movement. It will switch from defrost to feet vents, and when you put it on dash vents, it still blows out the defrost but at a much lower rate.

I still can't find the line #5 on the diagram. I did find #2 and it looks ok. I can't really see anything that looks bad from under the hood that goes to that point in the dash with the hvac controls, but maybe that's because I am new at this:


Maybe one of you will see something I can't.

 

So I double checked line #2 in the diagram in the first post. There are actually TWO hoses/vacuum lines that run there, one is much smaller than the other so I thought it was a wire. It is not connected to anything on one end, and I am not sure it broke at the end or the middle. And I can't figure out where it goes.

Here's a picture:


and assuming it didn't break in the middle, the loose end was pointing down here:

And the other bigger line is plugged in there. But I can't find anything the loose one goes to, and the diagram doesn't say what that is.

Any ideas?

 

Pretty sure that one went to the cruise control on my 96 . Mine was doing the vent change to defrost and turned out to be the check valve coming right out of the intake om the passengers side . It held vacum blowing through it but i happened to have another handy and changed it anyways and it solved the issue . Also while searching for vacum leaks there was a check valve under the dash close to the controls that I could unplug and it would instantly blow defrost and if I covered the vacum source with my thumb I could hear the door move and the vents would work
good luck

 

Thanks do much! I read about check valves being an issue for this on acceleration, but I didn't know it could affect it otherwise. So to verify I am looking for this under the dash somewhere between the hvac controls and the doghouse (picture from another thread looking for that part):

and there is another one near the intake on the passenger side under the hood. I didn't find this when checking lines yesterday, but I will try again today.

Mopar says this part us discontinued but it looks like I can take my chances on amazon or ebay.

 

Yep , that is the one under the dash I was able to unplug and cover with my thumb to get the vent to switch . The one coming directly from the intake was the bad one though. I missed it on first inspection because it hid nicely under the larger pcv valve hose
yes I heard the valve was discontinued also but I have a 96 dakota that I took the ac out of a few years ago so I borrowed its check valve to confirm . If you have a salvage yard or a pull your own yard i'd just go get a few
also I was able to reach the under dash check valve from underneath, it wasn't too far from where it came through the firewall . It is very small

 

Ok, I ordered the part and I looked again, but still can't see it. Am I looking in the right place, and am I missing it completely? I am new at this:

It still bothers me I cannot find vacuum line #5 from the diagram in the first post. I feel like the check valve is probably on that.

 

Mine came out of the intake about midway back on the manifold, you have to take the lower air cleaner section the whole way off to get a good view .
As far as the number number 5 line it looks like the one I also followed to the vacum resivour . That thing that looks like a ball . They crack alot but luckily I was able to check the lines visually from the bottom because a have a rear ac unit blocking access from the top . The resovour is #4 on the diagram , its tucked up under there but maybe you can see better from the top than I could
also thinking there was one golden vac selonoid under the glove box that a line went to, ill check later to see

 

Thanks again, very helpful. I had found the reservoir from the top earlier, but I couldn't see a line coming out if it from that viewpoint. I will crawl under again later when I can make one of my kids help me, but the last time I was under there, I didn't see it then either, but from what you are describing maybe I need to be further back?

This is what I saw then from underneath:

So I need to scoot further back towards the top of the picture to see that line and the check valve?

I have the added complication my driveway is at a steep incline so I have to work on the van curbside on the street. Which is not a big deal except when I get under the van - then I really need someone to spot me to keep from getting run over, ha ha.