2nd Gen Non-Engine/Transmission Heater/AC Airflow

[MStearns]

Looking for some help diagnosing a heater/ac issue. All of a sudden the airflow out of the vents is wrong. Defrost works fine, Defrost + Foot vent works fine, Foot vent alone works fine, however Foot vent + Panel vent does not. Instead of getting air flow out of the Panel vents it comes out of the defrost vents. When selecing Panel vent alone again it comes out of the defrost vent instead of the panel vent. On Recirculate, it apears the recirculation door is opening fine but again, all of the air is coming out of the defrost vents vice the panel vents. I suspect one of the flow control doors is not moving as it should. Given that all of the other doors seem to be opening and closing I don't think I have a vacuum issue. Is it possible to get to these to trouble shoot without completely removing the dash?? Looking under the dash I can't see much as all. Can I go in through the knee panel on the drivers side and get to anything that might help?

 

[WestTN]

Check for a vacuum leak.

Defrosters have been required by law since 1964 or so. Therefore the system is spring loaded to the defrost position to meet the law regardless of control system failure. Vacuum operated motors selct the other options such as heat to the floor, etc.

 

[MStearns]

The floor heat and defrost flow turn on and off, that is why I am afraid it is something more sinister than a simple vacuum leak.

 

[GAmes]

It sounds like the vacuum actuator for the door that sends air to the dash vents has failed. The billows get a hole in them and the vacuum escapes rather than pulling the actuator closed. IIRC the one you need to look at first is near the skinny pedal. Pull the vacuum line off, I think it is yellow, and check to make sure that you have vacuum. Manually actuate the door to make sure it is the right one. A word of caution. If you need to replace it be super careful you don't break the plastic connection piece on the door.

 

[MStearns]

Your right on the money! Oo. Actuator right above the go pedal. Yellow vacuum line has vacuum. With the truck running and the panel vents selected, when I manually move the actuator it holds in position and air goes like it is supposed to. It holds steady as I move between Panel vents and Panel and Floor, but as soon as I select something that turns the panel vents off it releases and then will not move again unless I manually move it. I am going to assume this means I need a new actuator although one would think that if it holds it open when it is manually moved that it should open it like it is supposed to.



Do you know of a good source for these? I checked Rock Auto and can't find one on there web site.

 

[GAmes]

I got mine at the dealer, quite awhile ago. I think it was less than $20. You might try a u-pull-it yard. The actuators are the same on 1500s. That will also give you a chance to see how to do it without breaking anything. I did something wrong (can't remeber exactly) and ended up having to pull the dash and split the HVAC to put the selector door back into place. I had inadvertantly pulled the hinge (support?) out. If you do it right the hardest part is twisting your body t see under the dash. Pulling the seat out may not be a bad idea. Good luck.

 

[PRohr]

This really similar to a problem I have been plagued by with my wife's Durango... . defrost works but if you select panel then the only position it will switch to is defrost..... I have vacuum at the line and at the dash connector. I was thinking the switch at the dash was bad and bleeding off vaccum as it's a random thing.

 

[MStearns]

I just found one on Moparparts.com for $35. Thanks for all the help!