HOW TO: Fix stuck HVAC mode door\actuator
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Author:  ajohns1288 [ Fri Jun 12, 2015 8:10 pm ]
Post subject:  HOW TO: Fix stuck HVAC mode door\actuator

There are a few other topics on this issue already here. I went though and snapped some pics as I went, so hopefully these will help someone.

This how-to assumes you already know you have an issue with the mode door linkage, either the door is stuck or the linkage popped off the track. Refer to the following how-tos for more info:

Blend Door Actuator diagnostic & fix - KKomodo & Scar0 - viewtopic.php?f=88&t=76917
Blend Door Actuator Motor replacement - joeS - viewtopic.php?f=88&t=72544
Center Dash Bezel (around radio) removal - Diggerfreek - viewtopic.php?f=104&t=36253

1: Remove drivers side knee bolster, kick panel (2 scrivets), center bezel, and radio (4 philips head screws)

2: Remove blend and mode door actuators. (4 T20 screws)

3: Remove actuator shield (3 T20 screws)

4: Remove mode door actuator linkage if it didn't fall off

5: Remove center vent (3 philips screws) and stick hand down to reach door. Try and move it to get unstuck.

6: Try to turn the two gears on the side of the HVAC housing. if they turn freely, you're good.

7: Put the smaller/lower of the two white arms on the housing, be sure to mesh the big tooth on the gear to the slot in the arm.

8: Put the bigger/upper arm into the outer track of the cam (spline side out). Carefully move the assembly into position and place the cam on the housing. Make sure the lower arm goes into the back slot on the cam and the bigger arm meshes correctly with its gear.

9: Carefully put the shield back on, wouldn't want to knock of the actuator we worked so hard to align. Do not test the linkage until the shield is back on. They will fall off and you will get angry. :furious:

10: Once the shield is back on and tight, move the linkage by hand to make sure it moves freely. If so, you can put everything back together, if not, you'll have to take everything apart and make sure the linakge is put together right. :banghead:

11: If it still doesn't move, chances are something is very broken. You'll probably need either new linkage parts or a new HVAC housing.

Author:  Scar0 [ Fri Jun 12, 2015 8:26 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

Nice write up!

Author:  lfhoward [ Fri Jun 12, 2015 9:00 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

Fantastic Job! This is an issue that seems to be cropping up on more and more KK's as they age. Glad to have the how-to for reference in case it happens to mine.

P.S. Added this to the How-To's Index. :mrgreen:

Author:  RyanMaasMN [ Thu Jul 14, 2016 10:26 am ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

This is exactly what I was looking for. Thanks!

Author:  chelsey12 [ Sun Sep 11, 2016 2:07 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

Great job. Thanks for sharing this i was looking for such kind of information.

Author:  libr872 [ Thu Feb 02, 2017 11:30 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

Is this the reason why I would have no air flow coming out of floor vents?

Author:  larryp1962 [ Tue Jul 25, 2017 8:58 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

I need the diagram of the lower gear placement for actuator below in picture

Author:  lfhoward [ Sun May 06, 2018 6:13 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

Well, I think the unthinkable has happened. After hearing a loud *POP* the HVAC mode is stuck on feet.


I took this photo after removing the mode door actuator. The actuator seems to work fine. The big black gear on the HVAC distribution box seems broken though. You might have to zoom in to see it, but it looks shattered.

So, is a new HVAC distribution box and a complete dash disassemble in my future? :POPCORN:

The distribution box (#8 in the diagram):


Link to it: https://www.factorymoparparts.com/oem-parts/mopar-distribution-box-68004022aa/?c=Zz1odmFjJnM9ZXZhcG9yYXRvci1hbmQtaGVhdGVyLWNvbXBvbmVudHMmaT1URzA3MDg1NSZyPTgmYT1qZWVwJm89bGliZXJ0eSZ5PTIwMDgmdD1zcG9ydCZlPTMtN2wtdjYtZ2Fz

Author:  lfhoward [ Sun May 06, 2018 6:48 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator


Video explanation of why this happens and what has to be done to fix it.

Author:  lfhoward [ Mon May 07, 2018 4:12 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

After watching some YouTube videos about dash disassembly for heater core replacement (since the heater core is inside the distribution box that needs replacing), I think I’m going to save up and have this done professionally. The A/C compressor is beginning to fail also (unrelated but also expensive) so I’ll try to get those jobs done at the same time, later this summer.

A good dash removal video:


Author:  lfhoward [ Tue Aug 21, 2018 2:30 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

I’m going to post up my experience to enhance the already excellent information here. Maybe these details will help someone down the line. I ended up doing the job myself to save $1000+ in labor costs. Here are some pics to prove it really happened.

This is the air distribution box that I put in. It’s new from Mopar. The new heater core goes inside of it, and I’m reusing the actuators and plastic attachments from the old box.

This is the seal kit. Since I didn’t also remove the AC evaporator unit I didn’t use everything in this kit, but it was needed for the distribution box and heater core pipes to make a good seal.

I did the surgical procedure on my Jeep in my parents’ barn. This is not a project that can be done while parked on the street as it takes several days and there are many interior trim parts to lay out in an organized fashion so you can remember where everything goes.

First, disconnect your battery for 30 minutes before starting the project to protect your airbag system.

I started with the bezel around the radio and climate controls. You can see I labeled every wiring pigtail so I knew where it goes for reassembly.

Center console was next. I also taped the screws and other hardware to the parts they belonged to, so that there were no stray screws or bolts at the end of the process.

I discovered why my parking brake doesn’t work very well. This will be a future project.

Removing dash trim. Follow the instructions in the video & this Lost how-to.


Radio out.

Speedometer out.

Airbag out.

Steering wheel & clockspring out.

Dash ready to come out.

Dash out. You can see the air distribution box now.

Before removing the air box you’ll need to remove the heater hoses from it inside the engine compartment.

Air distribution box. Evil on the left/top. Good on the right/bottom.

The hardware from the old box got transplanted over to the new. The exception was I replaced the 10 year old heater core with a new one since I was in there already.

The plastic holding the heater core pipes is part of what gets transplanted over.

I made sure I knew what settings I left the climate controls in (full cold, all feet) so that I could install both actuators on the new distribution box and verify that the flaps were in those positions. No climate control recalibration was needed at the Jeep garage, as it works exactly as it should. (Save $100).

The doors on the old box were glued shut by black goo that was made of melted rubber insulation. This causes the plastic gears on the box to fail. The new one will eventually have the same problem but hopefully I will get another 10 years out of it.

New box assembled and ready to go back in.

Getting it correctly in position without removing the entire AC unit was challenging, mostly because the box refused to seat properly into these 2 plastic tabs in the back. The ultimate solution (and I tried all sorts of things) was to prop up the tabs with a chair rung under them (any dowel will do) so that the box tabs could slide into the holes. Once they went in, I slid the rung out to the left and seated the rest of the box. This may not make sense until you see it, but if you ever do this job you’ll know what I mean.

Reassembly took only a few hours since I had all the parts layed out logically on the barn floor, screws and bolts taped to them, and all the wire harnesses were labeled.

The steering wheel went on last.

Reconnected the battery and... she lives!!!

Lastly I made sure the heater hoses were connected in the engine compartment and ran the engine for a while with the radiator cap off to get out the air bubbles in the cooling system. The water pump pushed hot coolant into the heater core so I could feel heat coming out the vents after the engine reached operating temperature. I topped off the coolant with HOAT (use Mopar or Zerex G05) and kept an eye on it for several days. No problems and it all works now like when the Jeep was new!

Author:  WWDiesel [ Tue Aug 21, 2018 10:40 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

Good Job!
Replacing a heater core on most any vehicle is truly a PITA job that would make a preacher cuss. :furious:
Heck, I traded one vehicle, a car, just so I would not have to replace the AC evaporator core. Book listed 14 hours to change it out. :shock:
After I traded it, dealer mechanic who I knew, it took him 3 days to change it out. He give me heck for trading it in.... :ROTFL:

Author:  JoeysDad [ Wed Sep 11, 2019 12:18 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

Moderator! Help!
Please remove the last 8 posts that snuck on here today. They do not belong here!
Suspicious as well....

Author:  JoeysDad [ Wed Sep 11, 2019 12:30 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

Looks like he's up to 23 posts now.

Author:  JoeysDad [ Wed Sep 11, 2019 2:29 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

Well, here I go again. I forgot to save my last draft, and sure enough, vanished after I paged back.

Again, thanks to lfhoward and ajohns1288 for the great information in these threads. Extremely helpful.
I do have the "Service Manual", however, it is very sketchy and has some errors and lot's of omissions.

I just completed this job yesterday on my wife's 2012 KK.
Last Spring she complained of low AC air flow, and only coming out of defroster vents. Mode switch did nothing. Blend worked fine.

I got underneath and found that the actuator was turning. Further parts removal revealed stripped mode door gears, one per door,
and jammed mode doors. At the time, I forced the mode doors such that air only routed to the upper vents, and disconnected the linkages.
I ordered the distribution box and the seal kit.
Since the FLA weather was too darned hot, I decided to wait until fall when I'm in NC. So here I am.

So here, I'd like to add to this thread things that I found during the experience of doing this job.

One of my goals was to NOT disturb the HVAC housing itself which contains the evaporator!

First, the distribution box that I received from an online Mopar dealer (ebay), was not quite in as good a shape as I expected.
Some warppage had obviously occurred, as the two halves did not seem to fit together real well, and as the heater core opening
was not real squared.

I recommend purchasing this box from somewhere that you can inspect it before taking it to its new home.

I highly recommend having the following tools in addition to what most of us already have:
A panel prying tool. (absolute must)

A parts grabber. Mine has a magnet at the end as well as prongs, and a little LED light.

An inspection mirror.

A headband type LED flashlight.

A 13 mm deep socket (a must)

A pair of steering wheel puller jaws that will fit into the 3/8" square holes on the steering wheel. (Autozone lends a pair,
I believe they are "OEM 27312".

I wish I had had a 1/4" ratcheting offset box wrench like this: https://www.homedepot.com/p/Klein-Tools ... 481400-_-N
which I then would have used with a T-20 torx bit to remove some of the tough to get-to screws on the air box. Instead, I turned
the torx bit with a small adjustable wrench.

Some pipe thread sealant for the threads of the coolant bleed screw for filling the cooling system.

A pair of very small alligator clip leads. (In case you need to turn an actuator like I did) and a 9V battery.

Things worth mentioning:
There is no need to remove the passenger air-bag, or the grab-handle below it.

Things are a lot easier if you unbolt the drivers seat and move it back a few inches.

Make sure you note the positions of the mode control and of the temperature control knobs.
Be sure you know how to match the mode door positions to the control knob settings.
On mine, my blend door/control was on full-cold, and my mode door for the upper vents was open and my mode door for the
defrosters was closed, and my mode control was set to upper vents only.

I did not remove my steering wheel from the steering column (did not have puller jaws that would fit). There is enough
room to extract the steering column and attached wheel if you move the driver's seat rearward. I did end up popping the
wheel off later just to make it easier to reinstall the column. This is optional.

I removed the backing plate that sits just above the pedal support bracket before pulling the dash. It attaches to 2
studs at the top of the pedal support bracket, and 2 additional phillips head screws.

I popped off the plastic panel that the radio sits on top of. This makes it easier to find a resting place for the dash once
it's removed.

Don't forget to notice the small single-wire connector that attaches to the evaporator temperature sensor on the HVAC housing
in the vicinity of the glovebox opening. I did. And ended up yanking the sensor out of the housing. Fortunately, nothing was

I found it much easier to deal with the portion of the wire harness that passes thru the firewall on the right side, vs removing
the entire harness from the dash. Find a connector attached to the top of the splash shield above the right front tire.
Pop it off (2 clips). Disconnect it and fish the wires into the engine compartment. Remove the air filter box. Underneat, find
a yellow connector. Undo it. Pop the remaining harness clips between that connector and the firewall grommet.
Pry off the firewall grommet from inside the car. Pull the wires through into the car. Done.

I chose to leave the dash assembly in the car after I disconnected it. You can do this if you pop the clips that hold
down the portion of the wire harness that runs along the center console. This will allow you enough slack to swing
the entire dash over the shifter and rest it upside down across the two seats. Helps to have the emergency brake handle down.

I highly recommend maneuvering the dash with a helper. I did it by myself, and was real proud, but then as I was trying to better
adjust the position of the dash on the seats, I managed to slice my hand open on the sharp edges of the metal dash sidewall.
6 stitches later, I was ready to proceed.

Once I started on the old air box, discovered the fun of trying to remove the T20 screw that attaches the heater pipe bracket
to the HVAC housing. Ended up using a 1/4" T20 bit and turning it with a little adjustable wrench.

Once I removed the heater core, I flushed it with a garden hose. It was like brand new after 120K miles. I guess flushing the cooling
system every 24K miles is good for something.

I found it very difficult to install the old heater core into the new box. The opening was not really square. The gasket on the core just didn't
want to pop over the 4 tabs on the box. I ended up applying a bit of grease to the gasket at the tab locations. Don't try to force this
as there is not a solid place to grab the box.

When I went to install my blend door actuator (which I thought was synchronized to the full-cold position of the blend door,
I found that the actuator shaft was about 5 degrees in rotation off. Not sure why. So.... I grabbed a couple of tiny alligator
clip leads and attached one end of each to the connector pins on the actuator. I was able to rotate the actuator by touching
the other ends to a 9 volt battery. (we called them "transistor radio" batteries in my day). If you need to reverse the direction
of rotation, simply reverse the leads.

To install the new box, I found it easier to shave down the "shark fin" that protrudes down in the center of the box between the
two arms that grab the tabs on the HVAC housing. I also did as was suggested in one of these threads, and propped up the tabs
using a breaker bar. (Didn't have a spare chair rung...). Only took a couple of tries to seat it.

Installing everything went pretty quick. I laid everything out in my basement in the exact order that I removed it.
I did remove the steering wheel to make reinstalling the steering column easier. Even then, I recommend a second set
of hands for this.

Hopefully these notes will help the next victim. Not sure if I would have done the job if not for what was already written here.

All in all, this car has helped me keep my mechanic skills honed, more than any I've ever owned...... except maybe for my 63
Plymouth Valiant convertible that I owned in the 60's.

Good luck.

Author:  lfhoward [ Wed Sep 11, 2019 9:23 pm ]
Post subject:  Re: HOW TO: Fix stuck HVAC mode door\actuator

Fantastic work! :rockon:
Thank you for posting these tips. I know it will help the next person who needs to do this job.

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