I adjusted my idle, and afterwords the A/C only stays in Defrost and the Controls do not work. Should I look for a specific vacuum line to repair or is it unrelated? I'm sorry I did not search, I'm preparing for a long trip tonight and want to try to fix it before I leave. BTW this is on a 98 12v.

Thanks,
Nathan

 

Should be totally unrelated as the engine goes. No computer controls on the engine, or any vacuum lines, other than the ones for the cruise control.

You might have pulled one vac line loose while adjusting the idle, so I would look around that area.

 

I thought they had a single vacuum line going into the cab somewhere on the firewall? Seems I worked on a dodge pickup years ago with some sort of a/c vent door problem and it had a single hose with a check valve in it. It may have been a gasser that I worked on. Check valve was to keep the vacuum from decreasing in the cab lines while accelerating. Vacuum could be pulled but not vent out from cab. I'm not sure about the diesels though, but back in 98 a dodge truck with electrically controlled door actuators sounds unlikely.

The actuator for that may be down on the box near the fuel pedal towards the middle hump or on the opposite side. If it has hoses you can trace it back and see if you have vacuum to it, if it is electrical you'd have to check and see if you have power and ground on your actuator. There will most likely only be three(?). One would be your fresh air and recirculate, mode actuator which should control upper/lower/defrost and then you'd have a temp actuator which controls your heat/cooling. You need to find the one for the upper/lower/defrost. Best thing when you find one you can manipulate it with the fan going and feel what it operates. I'm not a dodge mechanic but worked on cadillacs for years. On the older cadillacs that had vacuum controlled actuators they had a central block where the vacuum from the engine came into, then it routed the hoses off this block to the different actuators. This on the caddy's was a computer of sorts.

Hopefully this will give you some ideas, again, not sure about the vacuum line to the firewall. Best to crawl under your dash and look for hoses or wires then you'll know. The electric ones on the caddy's did go bad and would stay stuck in one position, but again....this is a dodge so maybe not exactly the same but should be similar. Hope this helps.

Shawn