i try.
give us an update when you get around to investigating and hopefully fixing the problem.

 

This is a great forum. I've been lurking for a while and searched, but couldn't find the same symptoms posted I'm experiencing, so figured I post them.

I have a 01 Dodge 1500 Quad cab 4X4 with a 318. Really good truck and it's been a solid, dependable truck, but my air vents are starting to act really screwy.

It seems the vents have a mind of their own. When on a/c or just vent with the blower on and the selecter set to blow out of the dash vents, the air swaps from the dash vents to the defroster. It does this constantly, sometimes every couple of minutes, sometimes longer. It never blows out of both the vents at the same time, and it blows out of the defrost about as much as it does the dash vents. It always blows out of one or the other, I just never know which it will be.

Oh, and I have never seen these symptoms on any other setting than the dash vents selector. I hope that makes sense.

Has anyone ever heard of this? I hear a lot of left side vs. right side cooling issues, but never dash vent to defrost. Any help would be appreciated.

Sparky

 

got a 1999 ram 1500 with the 5.9. all heat/ ac controls work fine blows out of whatever vent i have the control set to. Soon as i go up a hill or i punch it the heat switches to the defrost, once your off the gas you hear the blend door bang shut and go back to whatever setting you have the heat at. I already hooked my vacuum gauge up to the vacuum reservoir and pumped it up to 15 pounds and it holds at 15 pounds so the reservoir is holding fine. Hooked the gauge up to the line leading to the reservoir and its at 20 lbs. so i have vacuum but im at a lost why its switching to defrost. Any ideas?

 

Yeah had a brain fart forgot about the search feature lol my bad. Found a bad check valve at the intake, removed the two check valves and pumped with smoke just to make sure i had no leaks or lines we forgot to put on seeing as how the motor has 36 miles on it, just put it in. Prob was happening before the new motor though. Problem solved sorry for the double post

 

here is a couple other vac leak locations for anyone that still can't find them.

this one is the cruise control servo under the battery. the clean black plastic line is a vac line that runs to the passenger side of the intake manifold. it will crack or break sometimes. also the entire servo will develop cracks every now and then from battery acid dripping on it. so look it over really good.


these red and green vac lines are connected to the cad unit on the back of the front axle, they leak sometimes too.


and this one is where the cad unit bolts onto the front axle. it will have one wire plugged into the left side of it, a black vent hose on top and two vacuum lines plugged into the right side, you can follow the vacuum lines to the transmission mount in the picture above.

 

I have the same wild vents and will check the CV's. I also have a humming coming under the middle of the dash when ever I stop a light. Do you think this is a vacuum problem.

 

well i checked and the one going into the intake manafold leaks when I blow into it so I will go to the dealer to get one.

Also can anyone tell me what should be on the end of this hose that has a bolt in it. I just noticed it was not going to anything.

 

the PCV valve fixed the vents for me.
that hose is attached to your evap purge solenoid. it shouldn't be plugged off. i don't know if that is the line that goes to the tank or if it is the vent hose.

 

Ok thanks. I thought I was missing something.

 

i wouldn't unplug it until someone with a 97 or older ram tells you where it goes.