Cruise Control and A/C problems

05-20-2004, 08:47 PM
I have a 1997 Ram 1500 extended cab 2WD with 360 V8 and the cruise control doesn't work. I have been told that it is a vacume line and if thats the case, could someone please tell me where the line may be located? Also, when i have my A/C on with the vents switched to the position when they blow straight out into the cab of the truck and i accelerate, the air stops blowing through the front vents and begins blowing through the vents in the windsheild. Then when I let off of the gas, it goes back to normal. Any ideas? Maybe another vacume line? Maybe the same one for both? Please help!

05-21-2004, 01:44 AM
Maybe it's the TPS, seems to be quite a problem so I've been told. I've also been told that you can get one at autozone. I hear they are expensive though.

05-21-2004, 01:56 AM
Please donít count off for spelling.
Sounds like it could be a vacuum problem. Vacuum is just pressure below atmospheric pressure. Usually a large vacuum leak causes the engine to overspeed.
The controls for the air flow usually default to defrost with loss of vacuum. (to keep the window clear in cold weather). A major vacuum leak could rob both systems, the cruise control and the air flow routing.
There is also a great deal of electronics involved in the cruise control. But check for a vacuum leak first. Look for black hose,smaller then your little finger that is cracked or split. Dont take any off till you have new hose of the same size on hand. Squirt a small amount of motor oil on the suspected leak when the motor is running, it will suck the oil into the leak and temporally slow the engine back to normal idle speed.

If you are more adventurous, you could use starting fluid. Squirt a small amount of starting fluid on the suspected leak, when it hits the leak, the engine speeds up. This is very dangerous and could cause a fire. This is very dangerous and could cause a fire..This is very dangerous and could cause a fire..
Good luck

05-21-2004, 03:08 AM
Forgot to say where the cruise control was. On my Dodge 99 5.9 the cruise control unit is located below the battery in the front drivers side of the engine compartment. Two lines come from there and go to the middle of the engine below the air filter housing and to the left side of the throttle body. The smallest one, about 1/8 inch in diameter, is the vacuum line. It comes from the intake manifold. Check the connections on each end. Be careful, the line is hard plastic and could break easily.

05-21-2004, 05:37 PM
I don't know about the TPS (sounds like something that I typed on another post {are u making fun of me?}). I just replaced the TPS and i wouldn't think it to have anything to do with the a/c. But I do know where the cruise control module is. I have seen it many times. The battery that I had in it before leaked and it was replaced and the cruise control didn't work then either. I haven't noticed any holes in the vacume line but the module may have been damaged. I have heard that those lines are in a bad place because of the battery. But I have also heard of a few other problems with the dodges as well. Thanks!

05-22-2004, 12:28 AM
LTJGWorth, yeah I was just giving you crap. Don't take it personal though.

05-22-2004, 06:12 PM
Check the passenger side of the intake near the center for the vacuum leak.

05-28-2004, 08:43 PM
A leaking vacuum hose can cause both symptoms. Find the hose going into the cab, many times they rub on the ac line clamps. If not there, follow them to there ends.

05-29-2004, 08:19 AM
I had a dodge that had that exact same A/C problem. I took it to the dealer and a $45 part fixed it. I seem to remember it being some sort of valve. It has been a few years ago. I would just take it to the dealer or a PepBoys.

Good luck,

05-29-2004, 10:20 AM
Look under battary there is a c. control servo check the vacuum hose you are going to find the problem there for the a/c and c. control

06-05-2004, 02:52 AM
There has been a TSB issued for this problem, it is "TSB 08-22-97 Rev A". You can read it at or any dealer can run it off for you. It's caused by a damaged hose at the speed control servo located under the battery. The way the battery tray is designed allows acid to drip onto the hose and servo.The TSB will show you a diagram and give detailed repair instructions as well as part numbers if you need any. This problem is very common on the 96' and 97' models. It should also fix the air flow problem, just like gcarlg said in a low vaccume condition it will route air back to the defrost vents until enough vaccume pressure is present to operate the baffles in the A/C duct. Make sure to put a battery mat in the tray under the battery to absorb any acid in the future, they only cost a few bucks and if they had been used from the factory it would have eliminated this problem.

06-16-2004, 09:07 PM
Thank you for posting about this problem. My 96 has been doing this for some time now. I checked under the battery and sure enough the hard hose is broken off and is cracked in my places. Do I need to go to the dealer for the part, or is it a hose that can be bought from a part store?

06-25-2004, 07:57 PM
I haven't been on here to check this thing in a while. Thanks for all the help guys. I've checked the vacume line that was mentioned above and yep, it sure does have a crap load of holes in it. I don't know about the sensor though, but i'll look into it. And I'm asking the same question as TurboSW. Can I pick up one of those hoses at an AutoZone?

06-25-2004, 09:22 PM
I bought 4 feet of vac hose from Auto Zone in CA. It's rubber and not rigid like the stock one. To connect it I just cut off the ends of the old one and used them as connectors. You can buy new connectors fron the store, but this worked out perfect. One word of advise, before you pull the old cracked hose out of the shelve that holds the cruse Control cable hose, connect the new hose to the old one and feed it though. It worked like a charm. BTW the Hose ID is 1/8" and it looks stock. You might need a zip tie or two to hold the new hose to the Cruse cable, but don't zip it too tight so that air doesn't follow. Hope that helps.

06-25-2004, 10:15 PM
Funny you should post that because that is exactly what I did today right after I left this post. It fixed the a/c right up and it works perfectly, but the cruise control still isn't working. The servo may be damaged or the other line going into it may have a hole in it. It got dark on me and I couldn't check it (don't have a garage built). Thanks for the help.

06-25-2004, 10:24 PM
No problem. Sounds like we both have the same problem with the Cruse control. In another thread, it says to put a check valve in the hose by the intake area where we just replaced the hose. What the hell is a check valve?

06-25-2004, 11:02 PM
Yea I read that and printed out the diagrams. I have no idea what a check valve is but I am going to find out.

06-25-2004, 11:05 PM
Ok it seems that a check valve is a little valve (obviously) that you hook to more then one vacume hose at one time and it allows air to flow into and out of only one hose at a time depending on how you put it on. I think thats what it is but I'm just guessing. I didn't use one and I don't plan on it.

06-26-2004, 11:33 AM
Well, as luck would have it, I took the cruise control servo off of my truck and it has a nice (I would say little, but for the size of the servo, I'm not) big hole in the side of the plastic. I have searched the online shopping sections of AutoZone and Advance Auto Parts and they don't have it in stock. Is there a parts store that does carry it or do I have to order it from somewhere or go to the junk yards? I found one on ebaymotors, but it doesn't end for another 4 days and I'd like to get his job done because I am leaving for vacation in a week.

06-26-2004, 11:47 AM
In this servo is there a metal cable that runs into it? Do we replace the servo and cable? Just wondering if the cable comes off.

I wonder how the servo got a hole in it?

06-26-2004, 10:57 PM
There are 2 10mm nuts holding the cable to the servo and the servo to a metal plate (I found out the hard way that its probably easier to remove the 2 10mm nuts instead of the 3 10mm bolts holding the whole thing to the battery tray). So, all you have to do is take off those nuts, pull the cable a little and pull the pin out (be careful, I almost lost mine on the ground), pull the vacume line off, and then the electric control plug has a little plastic pin in it that I pushed through enough to grab it with a pair of pliers and then you can take the plug off and the servo comes out. I don't have a servo to put in my truck just yet and it runs fine without it. So the vacume there isn't that big a deal, but you can take up the vacume line that goes into the servo.

06-26-2004, 11:29 PM
Do you have the auction # for the servo? I want to see what it looks like. I searched for it, but nothing for Dodge ram came up.

06-27-2004, 04:21 PM
Yea the auction number is 7907746510. I could also take a picture of mine and show you whats going on with it if you like.

06-27-2004, 04:49 PM
here is my servo

Add your comment to this topic!