Recently picked up a 1999 dodge ram van 1500 with the 5.9. Been trying to troubleshoot my ac problems ( wild vents I think, only goes to defrost vents). I've did the blow test on the check valves and they seem fine, cruise control has no issues. I'm at a loss to try to figure out where this vacuum leak is. The only thing I've been able to find that may be off is the rubber stopper with the 3 hoses on the firewall. It has 3 hoses on the inside part, yet only 2 on the outside of the engine compartment side. Not sure if that is issue, or if there is only supposed to be 2 vacuum hoses on the outside. Hoping someone can give me some pointers. Thank you!

 

I've been having similar and same issues with my '99 3500, even changed out the check valves (one off the side of manifold and the other at the diverter block thing under the dash that goes the the dash control... and they are different in size too) but had no luck.
I have 3 lines through the firewall, one white which goes to the water valve on the heater core inlet hose and 2 blacks, one goes to the side of the manifold to a 3 way splitter and the other runs to the vacuum reservoir ball located under the the big black fan enclosure on the passenger side then routes over to the cruise control on the drivers side wheel well I think.
Hope that helps alittle bit. The only other pointer I can give is a temporary fix, dial the temp control over to full heat, listen for the vent door to switch then slowly turn the dial back to the cold side but not all the way. Stop 3-4 clicks short of full cold and leave it be. see if that helps prevent the vents changing during your normal driving, it helped mine.

Blackvan, thanks btw... had suggested inspecting the control itself in this thread at the end

https://dodgeforum.com/forum/dodge-r...emp-210-a.html

 

Awesome,that's exactly what I was looking for. It looks like it's missing the line that goes to the reservoir ball that you were talking about (farthest one to the right looking at the firewall) Going to take a look at it in the light tomorrow and see if I can trace that like down. Much appreciated!

 

Also, by chance would you have pictures of that reservoir for that third black hose?

 

Don't have any but will give a go tomorrow after work if you need it, pulling the headlight and shield just below should give a good view that vac line and try to give a better description for you. I think I steered you the wrong direction earlier because that line from the reservoir ball and whatever that valve next to it is, heads back up toward the manifold... not over to the driver side as I had stated. Sorry for that, my bad memory instead of going out to look!

 

Still not much luck yet. I have the white line farthest left, that goes to the 3 way to the intake manifold check valve. Then I have one black line in the middle that follows the firewall to to the passenger side to a control right behind the headlight.

 

Here's the 3 vac lines from the firewall, white is on right n 2 blacks left




white is connected to this water valve which is inline to the heater core inlet, the original one crumbled apart not long ago changing the heater hose so this is a napa universal one... one of the black vac lines is directly in back going to the check valve on the 3way




one black threads down behind the headlight as you said to this reservoir ball then the line goes n tees into this contraption next to it then heads back to the 3 way on side the the intake. That contraption has an electrical plug to it and I think has something to do possibly with the vents anyone is welcome to educate us if they happen to know...

 

Hmmm, ours are set up a little differently. The white one actually doesn't shoot over to the 3 tee. It goes around the motor the the check valve at the manifold and a 2 way. I did however do a smoke test through the brake booster and immediately saw smoke coming out of the white one. That may be a step in the right direction. You've been a great help Jfloors. Hopefully addressing that line will help some.

 

Glad you were able to find a leak to get you moving forward, will be interested in your progress.


We do have a lil bit different set up, I wonder do you have rear air in your van too? mine doesn't, it's a straight up cargo van front air only. Ya know what else Captain? I'm a ding dong your 2nd pic shows a black line going to the vent door control, I also have that and that's where one of the firewall blacks goes to. The other from my firewall goes to the check valve at the 3way (it's actually a Y type coupler) on side of the intake.This new pic shows it... check valve is at the bottom and 2 lines to the Y. One goes to firewall while the other goes down to the ball and contraption. I'm so sorry for any confusion i've caused for anyone that may read this but think I've finally got it correct!


Jim

 

Mine does have the rear air. Just got the van about 2 weeks ago. The ac was intermittent for the ride home, then just completely got stuck on the defrost vents after 2 days. I've put some tape up on the cracked lune for the moment (still at work). I'll give an update tomorrow if it made any difference.