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Discussion Starter #1
Here is the symptom: If the heat control is at the maximum heat position, I get heat. Any other position results in unheated air

I replaced the blend door actuator and ran the calibration routine. That did not resolve the problem. I have another vehicle with the same dashboard heater controls that does not have this issue. I am thinking of testing by swapping heater controls to see if that resolves the issue. Is there any other troubleshooting I can do?

The vehicle is a 2007 Dodge Grand Caravan with manual heating and AC, driver and passenger zones, plus rear heat and AC. The passenger side heat control works fine. The driver side control is the one with the problem. I asked this question in the Minivan-Pacifica forum and did not get a response, so I am hoping someone here has an idea on this.

Thanks.
 

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Quick question, when you move the driver's side temperature, does it sound like the blend door goes to full cold (running for a few seconds instead of just a short "burst")? If so, I would suspect the controls. I can research the circuits in my AllData and post them later, I am heading to a memorial service and will be gone most of the day.
 

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The slide potentiometers for the heater control can become 'intermittent' or inoperative from dirt, pet hair or dust, etc. Like a scratchy volume control that cuts out.
I wouldn't just spray a cleaner into the slide slot, I would take the control out of the dash and get at it more directly. The housing and circuit board does come apart. Handle components gently. The lighting may be by LEDs by 2007.
Cleaning the control is worth a try and the price is right. At this point, there is little to lose in a repair attempt. Use something like DeOxit and working the control back and forth?
 

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Discussion Starter #4
85lebaront2 wrote: Quick question, when you move the driver's side temperature, does it sound like the blend door goes to full cold (running for a few seconds instead of just a short "burst")?

I had not noticed. i will check and let you know. The van was taken on a road trip this weekend so I cannot test it now. I can say for certain that just moving the slider a fraction of an inch off of full hot immediately results in unheated air. If I removed the actuator and watched it, would I be looking for an extended run time of the actuator after only moving the slider a small amount? Not sure how it can go from full to no heat almost instantly. I am concerned the blend door is damaged, and flops between full heat and no heat.

ImperialCrown: I was going to give the slides a shot of Deoxit. I did not realize the control could be disassembled. That is also something I will try tomorrow.

I will be grateful if the problem is in an easily accessible component like the controls and not due to a damaged blend door.
 

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One can always hope it is something simple. If you remove the actuator to observe it, maybe you can see if the blend door feels damaged, as in flopping when you try moving the shaft. I don't know about the 2007 vans, our 2005 never gave us any problems. The only newer Chrysler I had to deal with was our niece's Pacifica, what a nightmare, evaporator leaked, almost the whole interior had to come out, nice Behr system, reminiscent of my time at the Mercedes-Benz dealer.

If I can post what I just saved from my AllData, there is a recalibration procedure for the actuators if they are replaced, if it works it does not require a DRB tool.
 

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Discussion Starter #6
Thanks for the info and the diagrams. The recalibration steps you posted are the ones that I had followed.
It seemed to complete successfully - it took a couple of minutes.

When I removed the actuator, I wanted to check the blend door, but I could not see where to manipulate it manually. The driver side actuator has a piece with teeth that fits on the actuator shaft. That piece seems to work somehow with a similar piece on the passenger blend door actuator.

From the Alldata info, it looks like actuator troubleshooting requires a DRBIII scan tool. If I do not make any progress on my own, I might have to have a dealer do the diagnosis.
 

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Good luck with it and hope it worked. I believe some of the other high end scan tools, like Snap-on sells and possibly some others may be able to read the diagnostics.
 

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Discussion Starter #8
Update:

1. Removed the actuator and moved the blend door manually. The blend door works fine. I can move it manually from unheated to full hot and it supplies the appropriate temperature air.

2. I compared my van to another Chrysler van with the same HVAC set up that is working correctly. I noted the position of the actuator gear and the blend door gear at full hot and full cold on the "good" van, and compared it my van. My van's actuator gear and blend door gear were out of position compared to the van that works correctly. I uninstalled the actuator and re-seated the actuator gear to the blend door gear, and reattached the actuator. I ran the calibration routine, and got the flashing light error after the calibration had completed. I looked under the dash, and saw the actuator gear and the blend door gear were misaligned again, not synced as the "good" van.

3, I tested with a different heater control, still got the same problem.

4. While the actuator was disconnected, I moved the slider control The actuator seemed to have a full range of motion when disconnected. When installed, the actuator gear gets out of sync with the blend door gear.

This seems like it should be a simple fix, but something in the system is confused. I am going to throw in the towel and have a shop with a DBIII scan tool read the error code. As a last ditch effort, would another actuator be worth trying at this point? If anyone has any ideas on what else to try or test., I would appreciate the advice.
 

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Discussion Starter #9
85lebaront2 wrote: Quick question, when you move the driver's side temperature, does it sound like the blend door goes to full cold (running for a few seconds instead of just a short "burst")?

Moving the driver's side temp control from cold to hot results in the short "burst" you described. The passenger side that works correctly runs longer going from cold to hot. Same behavior going from hot to cold.

Swapping in a known good HVAC control unit (and then running the calibration routine) did not resolve the problem. Maybe I will just try another actuator.
 

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. . . . I ran the calibration routine, and got the flashing light error after the calibration had completed. I looked under the dash, and saw the actuator gear and the blend door gear were misaligned again, not synced as the "good" van.
. . . . .
4. While the actuator was disconnected, I moved the slider control The actuator seemed to have a full range of motion when disconnected. When installed, the actuator gear gets out of sync with the blend door gear. . . . . .
I am trying to understand your comment "actuator gear and blend door gear misaligned / out of sync". See attached image.

Blend Door Actuator.gif

The actuator shaft has teeth on it. They are splined and constructed in such a way that there is only ONE way it will fit and mate to the receptacle on the blend door shaft. I am thinking there is a flat spot on the teeth shaft that corresponds to a flat spot on the mating receptacle on the blend door shaft? Are you getting the 2 mated correctly?

If you are getting the actuator mated to the driver side blend door shaft correctly, then maybe the issue is the mating receptacle on the blend door shaft that accepts the actuator splines is broken or cracked. During calibration the HVAC control pulses the actuator motor and detects it has reached its travel limit when it encounters some mechanical resistance. If the mating receptacle is cracked the actuator shaft continues to rotate and the torque causes a spread in the receptacle hub that allows the actuator splines to "jump teeth" and get out of sync????
 

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Discussion Starter #11
Thanks for the response. The teeth on the actuator are fine. It has a 1/4 round gear that goes on the shaft. The gear on the actuator then mates with the gear on the blend door shaft as shown below.






I viewed the cold air position of the actuator gear and the blend door gear on the van with the heating system that works correctly. I then reinstalled the driver's actuator on the broken van with the temperature control set to cold, and matched the position of the the actuator and blend door gears to those on the van that works correctly. I then ran the calibration routine. After doing that, the two gears were no longer in the same position as the two gears on the working van.

Based on the alldatadiy.com directions, the calibration should take care of getting the actuators and blend doors aligned properly. See the italicized text in the excerpt below.

The blend door actuator for the single zone heating-A/C system is located on the driver side end of the front HVAC air distribution housing, close to the middle of the distribution housing.

For the dual zone heating-A/C system, the same blend door actuator used for the single zone system becomes the driver side blend door actuator, which is mechanically connected to only the driver side blend-air door. A second separate blend door actuator is also located on the driver side of the front HVAC air distribution housing which is mechanically connected to only the passenger side blend-air door.

The front blend door actuators are interchangeable with each other, as well as with the actuators for the mode-air door and the recirculation-air door. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle. Each actuator also has an identical output shaft with splines that connect it to its respective door linkage and two integral mounting tabs that allow the actuator to be secured to the front HVAC housing. The front blend door actuators do not require mechanical indexing to the blend-air doors, as they are electronically calibrated by the A/C-heater control.

The A/C-heater control must be recalibrated each time an actuator motor is replaced.
When I manually moved the driver's side blend door, I did not notice any damage to the blend door gear. The gear that goes on the actuator looks fine as well. I will take another look at it, just to be sure. Thanks again.​
 

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Discussion Starter #12
Here are a couple of 30 second videos that I shot to show the difference between the van that is blending air correctly and the one that is not: Maybe someone will recognize this issue.

Van with HVAC blending working correctly.

Van with HVAC not blending - only unheated air or full heat air.

Stuff I've tried that has not resolve the problem:
Different actuator
New actuator
Tried the heater control. from the "good" van in the van that will not blend.

I am able to move the blend door manually and get a range of air from unheated to blended to full hot, so I do not think there are any issues with the blend door.
 

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Does the actuator have a splined shaft like in AllanC's picture, where one spline is deleted so as to align the shaft only one way?

And can you pull on that splined shaft and yank it out? I just replaced an actuator where the shaft was broken off inside the motor housing, looked OK with the splined shaft in place. But the motor did not actuate the door, because the sheared shaft was spinning in the housing.
 

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The 2005 RS Body Diagnostic Procedures manual should be similar to procedures for a 2007 RS. See p.691 for Blend (temp)/ Mode/Recirc door operation improper - dual & 3-zone MTC (manual temperature control).
They do have you check for DTCs (diagnostic trouble codes) at the beginning of the troubleshooting. Finding a DTC might save you some time and frustration and give you a starting point for diagnosis. See here:
http://oskin.ru/pub/chrysler-dodge/manuals/Service Manuals/2005_RS_Caravan_Voyager/2005-RS-Body.pdf
Wiring and connector pinouts are at the back of the book.
 

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Looking at your second video in comparison to the first one, there appears to be a raised "arrow" for lack of a better term and a mating notch where the drive (on actuator) and driven (on blend door) gears mesh. On the first video the gears have the arrow and notch where they line up as the gears rotate, on the second video they are not in alignment and the drive gear physically jumps as the arrow comes in alignment.
 

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Looking at your second video in comparison to the first one, there appears to be a raised "arrow" for lack of a better term and a mating notch where the drive (on actuator) and driven (on blend door) gears mesh. On the first video the gears have the arrow and notch where they line up as the gears rotate, on the second video they are not in alignment and the drive gear physically jumps as the arrow comes in alignment.
Agree with this assessment. I have created images from the videos. In the first image at the 15 second interval you see one sector deflect as if the teeth cannot mesh properly. Possibly debris in the teeth? In the second image the 2 sector gears mesh and turn properly. Use a small pick and see if debris present in the teeth.

Blend Door Sector Geared Operation Failure.gif Blend Door Sector Geared Operation Correct Mesh.gif
 

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Discussion Starter #17
I uninstalled the actuator and the gear and took a few photos. The shaft and the gear that fit on it do not appear to be keyed as in AlanC's photo.

I do see what you guys have noticed about the deflection in the video - thanks for catching that. The teeth that match up with the blend door drive (on the piece that fits on the actuator) are fine - no breaks or cracks. However, there does appear to be an index in the center that piece - I circled it in the last photo below. I am going to match it up with the center of the gear on the blend door, and see if that resolves the issue. I will let you know what happens.

Thanks again for the troubleshooting assistance.






 

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Good luck with it! I hope that solves it for you.
 

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Discussion Starter #19 (Edited)
I reinstalled the actuator with the teeth aligned between the actuator gear piece and the blend door gear drive. The deflection is gone, the gears operate smoothly. I did the calibration routine successfully with no errors. The problem persists, however. The actuator does not move until the temp control slider is at the full heat position. Once at the full heat position, moving the slider a fraction of an inch toward the cool temperature setting results in the actuator moving all the way to cold. I have either full hot or unheated air. Nothing in between.

I have tried different actuators and a known good HVAC control. The testing I have done, plus the reference that ImperialCrown provided leads me to believe that it is time to take it to a professional who has a DRBIII scanner. Is a DRBIII scanner exclusive to dealers, or will independent shops have that, too?

. Thanks again everyone for the troubleshooting assistance.
 

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The DRBIII has Snap-On and OTC/SPX tool equivalents that any shop may have. The DRBIII has been replaced by WiTech at the Chrysler dealers. The WiTech has a DRBIII 'emulator' which can be used on older vehicles.
An (approximate) $100 diagnostic fee may get you an answer.
The older NS (1996-2000) minivans allowed fault codes and tests to be performed by the dash controls. The newer minivans don't have that feature and require an advanced scan tool for access to and communication with the HVAC module.

I have found that 'jumped' teeth on the air door linkage can be from a binding or stalled door. This can leave behind an actuator 'overcurrent' fault code.
I have found pens, coins, children's toys, etc. inside HVAC housings that interfered with door motion. Small items left on top of the dash can roll into the defroster outlets.
 
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