1995 Dodge Ram; 1500; V-8; 5.9L; recently purchased from "single owner" perfectly maintained, 136K. Cruise control is ineffective and sluggish. At times I can set a cruise speed but the RPMs always drop down first, then when cruise control engages it will not match the set speed (always a few MPH less), and speed decreases and decreases after a while; the resume/increase option operates much the same. This problem coupled with: heater or A/C fan on vent, many times when accelerating the airflow switches from the vent to the defrost? All of this tomfoolery points to a vacuum issue, the cruise control servo hose from the vacuum reservoir looks good. I'm left to assume that a faulty vacuum reservoir is to blame. Do you know where I could get a new one or the part number? I took it off but could not find a part number on it - @$&*%! Thanks. BTW: New to the forum and my first post ... this is a very nice online community for Dodge people. Thanks again.

 

Cruise control servo under your battery on the driverside, most likely either is completely going out or has a vacume leak caused by a cracked or broken vacume line.

Also, the issue with your heater is going to be caused by one of the valves on your passengerside, look up wild vents or crazy vents and there are a buttload of threads about it and how to fix it.

 

Thanks bro....

 

Np let us know how it turns out

 

Mine did the same, replaced cruise servo with junkyard unit to fix the problem. It is below the battery, and it seems that battery acid/corrosion are prone to drip on the servo and ruin the internal diaphram.

 

SOLVED -- My cruise control is now working like a champ - yippy! I'm driving from Las Vegas to North Dakota soon and it will now be more enjoyable. The problem was a small hole in the cruise control servo tube/hose. And I do believe that the wild/crazy vent problem was solved too. I have another item and am using this forum and its knowledgeable members to troubleshot the issue. Thanks for being a part of this community and pointing me in the correct direction.....

 

when there is a vacuum leak the vents will default to defrost.

 

Glad we could help man thanks for getting back to us