Blend doors out of sync.

[teeje]

After I pulled the dash to do my heater core I noticed that my Vent modes are out of sync. Face works, but face and feet combo goes to feet and defrost. Is there a way to reset the actuators? They all move like they should no problem. Just certain positions are all kattywampus.


Sent from my iPhone using Tapatalk

 

[ltd02]

The position is defined by that wicked goofy vacuum selector if I remember correctly. Might have to unplug it and make sure it is connected properly and tightly. Maybe a slight leak? I remember when I pulled most of my dash apart for a blend door actuator swap my position selector acted funny for a bit but corrected. I was really paranoid about that connection. It just looked like a vacuum leak waiting to happen. I think there is a vacuum reservoir under the passenger side near the door. Make sure that connection is good too.

 

[teeje]

The position is defined by that wicked goofy vacuum selector if I remember correctly. Might have to unplug it and make sure it is connected properly and tightly. Maybe a slight leak? I remember when I pulled most of my dash apart for a blend door actuator swap my position selector acted funny for a bit but corrected. I was really paranoid about that connection. It just looked like a vacuum leak waiting to happen. I think there is a vacuum reservoir under the passenger side near the door. Make sure that connection is good too.

Yeah the vacuum reservoir is all good as well


Sent from my iPhone using Tapatalk

 

[CactusJacked]

Might be easier to re-label your switch. :happy175:
Seriously tho, try re-calibrating the blend door. Here's how, per the FSM: | Repair Guides | Control Panel | A/c & Heater Control Calibration | AutoZone.com

 

[teeje]

Yeah the vacuum reservoir is all good as well


Sent from my iPhone using Tapatalk

How did you're act funny? I just replaced the climate control unit and that didn't solve it either. Right now it's on recirculation and that part works but comes out at feet and top vents. If I switch to just the top vents it comes out from just the top vents


Sent from my iPhone using Tapatalk

 

[teeje]

For now I zip tied the actuator so it's just coming out at my face. That's all I use anyhow until someone can suggest something. The blend door is fine. It's the actuators that are out of sync


Sent from my iPhone using Tapatalk

 

[ltd02]

How did you're act funny? I just replaced the climate control unit and that didn't solve it either. Right now it's on recirculation and that part works but comes out at feet and top vents. If I switch to just the top vents it comes out from just the top vents

When mine acted up it took forever to change positions. Did seem to be worse for certain positions. Pretty sure it was a mild vacuum leak and it would stall between positions for quite a while.

 

[ltd02]

For now I zip tied the actuator so it's just coming out at my face. That's all I use anyhow until someone can suggest something. The blend door is fine. It's the actuators that are out of sync

The blend door actuator is a little motor, not vacuum. If it goes it usually fails at "cold", so you'll have no heat. I think everytime you shut your KJ down it defaults to "cold". I say this because when mine started going, I could get it to a "warm" position but as soon as I shut it down and started it back up it was stuck at "cold" again no matter where the knob was pointing. If the blend doors go/break then you could be stuck anywhere.

 

[teeje]

The blend door actuator is a little motor, not vacuum. If it goes it usually fails at "cold", so you'll have no heat. I think everytime you shut your KJ down it defaults to "cold". I say this because when mine started going, I could get it to a "warm" position but as soon as I shut it down and started it back up it was stuck at "cold" again no matter where the knob was pointing. If the blend doors go/break then you could be stuck anywhere.

Whichever it is? It's not the hot/cold blend door.


Sent from my iPhone using Tapatalk

 

[CactusJacked]

Did the heater control to blend door calibration procedure I posted above not do anything?

 

[Billwill]

The Heater control controls the heat setting using the Blend Door Stepper motor.

The Vent control is done by vacuum...if vacuum from the intake manifold is lost going into the cabin then the air only comes out of the demister vents. I had this happen to me on my CRD after a service at the Dealers...after picking up the jeep I noticed that air was only coming out of the demister vents...I went straight back to the Dealers and they explained that they had knocked off the vacuum pipe from the vacuum pump that the CRD uses.

The Service Manual for the KJ explains that the Blend Door motor moves a flap to control the airflow over the Heater Core to adjust the heat...no water valves are used on the Heater Core.

Then there are two Mode Door Actuators alongside the HVAC...operated by vacuum.
One Mode Door Actuator controls panel vents while the other controls the floor/defrost doors. So there is a vacuum line coming into the HVAC from the intake manifold and then vacuum lines connecting the Mode Door Actuators to the relevant vents...one of these vacuum lines may have been knocked off.

There is also a Recirculation Door Actuator to close off outside air...this is also vacuum operated.

Download the KJ Service manual for the relevant year KJ here and have a look at "Heating and Air Conditioning" Section:

Index of /manuals/Jeep/KJ

 

[teeje]

Recirculation door works fine and it switches over. I check all vacuum lines and they all seem to be connected fine. I'm not exactly sure what's going on. Defrost works fine, defrost and feet works fine, face only works fine but when on face AND feet it goes to feet and defrost. Max AC(recirculation) goes to face and feet. I never use any other function other than just face for the heat so I just zip tied the actuator shut so it's only on face. I noticed when I put it on face only, the actuator goes all the way shut but when putting it on face AND feet the actuator opens up all the way


Sent from my iPhone using Tapatalk