Ihave a 1997 dodge ram 318 and when i have the heater or air cond. on and i step on the foot feed, gentley or hard i loose all the vacum and whatever i have on will automatically shift and go to the defroster,also the cruise control being on it will loose speed on a hill instead of holding steady.If you run the vac hose directley from the engine to the heater system it works fine. we have put on new hoses and check valves but nothing seems to work.would like to no if anyone has had this problem and if adding the seccond vac. canister would cure it.If anyone can help me i would appreciate it. Thank you, bob

 

I had added a canister on my 95 Ram CTD. One thing to remember is that if you add it, then it takes longer to build enough vacuum when you first start the truck. If you have to make several start stop moves, you may run out of vacuum because the pump now has to evacuate a larger area.

I would check those lines one more time. My problem was the smaller, hard plastic line and not the rubber. Also, no offense, make sure that your new hose is rated for vacuum. Some hoses are designed for pressure only, and will collapse under vacuum. You said the check valves were replaced, are they in the right direction? How many is there, 2 or 3? Something like that.


Good luck.

 

I currently have the same problem, but haven't taken time to fix it. Here is a link I found that might be helpful.

http://autorepair.about.com/library/...e+control+work

Let me know if it fixes the problem so that I can fix mine.

joe