I have a Dodge pickup I use for a tow rig that's having problems that I believe to be vacuum related. First, here are the truck specs:

1996 Dodge Ram SLT 2500 Ext. Cab
360 ci and Auto Tranny

The first problem is the A/C vents. Under moderate to heavy throttle the A/C blows through the floor instead of the dash vents. Last night I checked all the vacuum lines under the hood and found no leaks. I spoke to another person that has a similar truck and he said he has the same issue with his so this is sounding to me like a common problem, not just a problem with my truck.

The second problem may or may not be vacuum related as I haven't crawled under the truck yet. I don't know if the heavy duty 4 speed auto is vacuum modulated or not, but it hangs in 2nd gear for a long time during moderate throttle. I have to lift my foot off the throttle and let it shift down then resume accelleration to get it to shift right. I have checked the fluids and they are at the proper level and it is in good shape, not burned or scorched.

I would appreciate any help you have in this matter! I

You a/c problem is actually a bit different from most, where the air goes from the dash to the defrost position. There are two common problems. The most prevalent is a bad check valve behind the dash, just under the cowl. The second is a leak in the vacuum system that is under the battery typically from leaking acid eating throught he hose(s).


As for your tranny, it is most likeyl related to the torque converter.

My battery is behind the driver's side headlight. Are there vacuum lines up there that I overlooked?

Oh, and also, it might be shifting to defroster, I really didn't pay a ton of attention as to where it was going.

I'll have to look into the hoses behind the dash. Hmmm, that sounds like a lot of fun! :)

Yes, there is the cruise control module under the batter tray. Have fun getting to that valve under the dash, it is way up there.

You might just need to adjust the kickdown a little for the upshift problem.

Sounds like I could trace back the cruise stuff and close it off for a while to see if that helps.

Sounds like a leaky vacum line somewhere.. or something like that... but with the transmission... your 518 (or do you have a 618?) is probabally loosing it's torque converter. I would get it checked out NOW. Or you could wait... I'll bet that in about 5-6k miles you wont be able to shift into reverse without giving the truck some gas and cherping the tires... Mine did the same thing.. and i had to pay $2200 (plus alot of headaches from a tranny guy who didnt know the tranny, and didnt have the tools to work on it) to get it rebuilt since the torque converter spit it;'s guys, got metal shavings everywhere, clogged up the tranny cooler (which I just by passed so I wouldnt have to deal with it) and thus oveheated the tranny to the point it was overflowing... ALOT. as good perventive maintance (something that isnt necessary, but I wish I had done it the day I drive my truck home) is to pull the tranny pan, replace the filter and fluid, and check for any sort of metal shavings. Also I would go and buy a tranny temp gauge. I bought a B+M one, and I really like it. Plus, it lights up when the fluid is WAY too hot. I mounted mine right next to the ABS box, and it Looks real good. Let me know if you want to see a pic of mine mounted... also the hook up was farily easy... took me about 2.5 hours for the full install... but more than worth it... Hope I helped some.. and keep some money for a new torque converter.. and maybe a rebuild too (mine had 60,000 miles on it when I had it rebuilt... started shifting wierd at about 54,000)

Garrett

I have the 618 I guess, I know it's not the same transmission that's in the 1500's. I really haven't investigated a lot on what tranny it has yet, but I know it has a 360 and a Dana 60 rear. :) A tranny service is on my list, I hope I can get to it sometime this week. I checked the fluid and it's in good shape, but I'm going to drop the pan, replace the filter and refill with Valvoline Synthetic Blend.

My dad said he thinks the vacuum problem could be confusing the computer for the tranny. I don't know if this is true or not.

The cruise is working fine, so I'm not sure that I have a vacuum problem around the cruise vacuum lines. I bought this truck from my dad and he said he replaced all the hoses under the hood to try to fix the problem (and he used the Dodge hose harness). He didn't know about the check valve in the dash so I definately need to check that.