1998 Dodge Ram

Does anyone have pictures or diagram of the vacuum actuator and door that switch airflow from the vents to defrost?

When I am driving up a hill, and the engine load increases, vacuum drops, and airflow will switch from vent to defrost. Then, even if I just lift off of the accelerator, the vent airflow returns almost immediately.

It's getting annoying, and I assume that door and actuator are only accessible when the dash assembly is out of the truck.

 

Look in the FAQ/DIY section for the 'wild vents' threads. The fix is actually cheap, and easy.

 

Not sure why but whenever someone tells me to look in the FAQ/DIY I can never seem to find whatever thread they're referencing.

If you're talking about the check valves, I've located and replaced them. I also did the other common issue and removed my cruise control and capped the line. (I didn't use it anyway.)

I feel like there is a vacuum actuator in the upper portion of the dash, above the fan, that can't be reached unless the dash is removed. I think there may be a leak at that actuator...if I am guessing correctly.

 

I think this is a common problem with 98 durango. Mine has done this the entire time I have owned it. I just removed the dash and replaced the heater core and evaporator. The problem got worse so I checked the Vacuum reservoir under the front cowl and it was fine. I bought a 12 volt vacuum pump and an adjustable vacuum switch so it will turn the pump on when the vacuum falls below a certain level. I haven't installed it yet but I plan to "T" into the vacuum line just after the brake boost and the line that runs to the cruise control motor. Make sure to check that all the check valves are good along that line just after the brake boost. Those are usually the problem. Mine all check out so I assume the vacuum reservoir is just under designed and there is a small leak in the AC controls or actuators.

 

Actually it's in the sticky section(first one).
https://dodgeforum.com/forum/2nd-gen...fan-speed.html

 

I actually fond that video on YouTube before the linked thread.

I've either addressed everything he went over or it didn't apply.

I think I have a vacuum leak at whatever actuator controls the door that separates the vent output from the defrost output.