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DIY fix for Jeep Cherokee A/C Blend Door Failure

Picture of DIY fix for Jeep Cherokee A/C Blend Door Failure
Like most DIYers I see a problem and the last thing I think about is "where do I take this to get it fixed?" I instead ‎look at a problem and try to outwit traditional solutions. That being said, when I didn't have heat in my Jeep Grand ‎Cherokee (JGC) during our first cold snap I naturally went online to diagnose and solve the problem. What I ‎discovered was this is a very common problem with my model of JGC (1999-2004). I love my Jeep, but the person that ‎designed this blend door actuator system needs to find new work. The design is inherently weak, and relies on a ‎calibration phase that puts intense pressure on the weakest points in the system. Not wanting to repair the faulty ‎design with the same OEM design, I set out to reverse engineer a long-term solution

This website was among the more helpful sites as it provides Jeep's Repair kit instruction.  Thanks for a well thought out site, and permission to borrow content.

http://www.denlorstools.com/autoblog/2010/03/jeep-grand-cherokee-dual-zone-blend-door-repair/

This site does a good job of where and how to cut, so I will not re-invent the wheel.  I'll show you my solution to the kit from Jeep.

Total Cost of Project:
$1.76  Mending plate ($0.88 x 2)
$3.36  Hinges ($1.18 x 2)

Required Materials / Tools:
4  - 1/8" rivets
1  - Rivet gun
hacksaw or rotary tool (the hacksaw requires more patience than I possess)
Drill
 
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Step 1: Problem...

Picture of Problem...
I was able to remove and manipulate the outside most blend door actuator, connector and door without any issue. I ‎could have fabricated all new parts reasonably easily, however the passenger side control would not have worked. ‎So I worked within the OEM connector parts to ensure dual climate control operation.

I decided on a standard 3 inch door hinge as my new pivot point. This stamped steel piece should be more than ‎sufficient to withstand the calibration forces. The door is a reinforcing plate typically used on decks and truss ‎frame construction. These both will be very easy to find at your local home center. The truss plate is found in the ‎pressure treated section.‎  You will need 2 of each to complete both blend door repairs.

Step 2: Solution...

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The concept of the repair is to rivet the truss plate to the hinge, manipulate the hinge barrel to work on the OEM connector, and cut everything to fit.  First I had to remove the pin from the hinge.  Use the side of the hinge that has 3 barrels, not the side with 2.  This will enable the connectors to reach in their traditional position.  Next, select a 5/16" drill bit and drill out the one of the outermost barrels in your first hinge.   

Step 3: Fit the OEM connector

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Using the OEM connector (the white piece) test the fit.  Mark a line where material is to be removed to allow the key to fit.  Remove material with a rotory tool or hack saw.  The fit between the OEM connector and the hinge has to be incredably tight.  The amount of torque that is aplied to this piece in insane.  Be patient, b/c you will probably have to install, test, remove and tighten several times before you get it right.

Step 4: Add Door...

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Select 1/8" rivets and drill required holes in the hinge to attach the door, and attach door.

Step 5: Trim to fit...

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Now that your door is assembled, trim it to fit using the old doors as templates.  These new doors will fit very well, and will not work if they are even 1/16" too large.  Be sure to pay attention to the side that the notch is removed from - It needs to be on the opposite side of the connector.

Repeat steps 2-5 for the other door. 

Step 6: Connect Doors...

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Cut the head off of one of the hinge pins to serve as the connector between the 2 doors.

Step 7: Install and test...

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This step requires the most patience.  To install the far blend door you will probably not be lucky enough to have the connector key in the right place.  No worries - disconnect your battery for about 30 seconds and reconnect.  This clears the Automatic Tempature Control computer and it will run the calibration test automatically.  Turn the ignition to run and turn the climate control on.  The actuator will begin to rotate clockwise.  Once the key is in the correct position turn off the ignition and disconnect the battery. 

Push the new door onto the connector and slide the connector pin all the way into the installed door. 

Install the second door, sliding the connector pin into the far side of the second door.  Align and snap in the near connector. 

Reinstall the near actuator and test.  When you put the ignition to run and turn on the climate control system it will run though the calibration test that broke the OEM equipment to begin with.  Watch the doors move, and pay attention to the amount of torque applied to the doors - the plastic ones didn't stand a chance!  Be prepared to remove and tighten the connector / hinge mating.  Once you are satisfied the connection is secure, duck tape the doors to cover the holes.  Replace the cut piece of plastic and tape, and you're finished.  Now...what to do with all that money you saved...hmm....

tallan14 years ago
I just wanted to say thank you for this, it saved me about $160. I spent less than $20 and about 2 hors of my time. If I could just add, the hinge that I used was one that the pin just slid out of , so basically one less step.
jeepbro tallan12 years ago
This is some good info, such a bummer it happens to so many JGCs. If you don't feel like making your own door/hinge, you can do what I did and put in a heatertreater It was cheap and still going strong after 4 years!
Gregmink (author)  jeepbro2 years ago
I'm not sure what a heatertreater is - care to explain?

I agree though - something so "simple" and it leaves such a bad impression on most Jeep owners.

Heatertreater is a brand of aftermarket blend door replacement or fix, instead of a Dorman or JGC Parts. That's all.

jimbrody8 months ago

Great instructions. I realize this is an older post, but can anyone comment on the dual zone control? Before cutting anything I manually flipped the outer door by turning the keyway with the motor free from the housing, it sounds like it is flipping open and closed as it should. Is there a second motor for the other door because of the dual climate control? I have the classic symptom of cold air on the passenger side. Also when I move the climate control knobs from lo to hi the motor moves the outer door. Can't tell what's going on with the inner door.

Gregmink (author)  jimbrody8 months ago
Yes, there are two servos - one that you accessed via the key way controls the drivers side. If I remember the research I did prior to cutting anything, the passenger side servo is installed into the heating and air "assembly" prior to it's actual installation in the dash of the vehicle. Accessing it requires removing the assembly from the Jeep, which involves getting past airbags and other stuff I didn't want to tear into while in my driveway.

I will say that with time the weakest point in the new system, the white OEM connector piece, failed and was stripped. So I had to epoxy the drivers side connector to the new door, hinge pin and passenger side door. I now only have control via the Driver's side temp control, but I almost never have passengers so it's not a big deal for me. I love the Jeep, but way too many plastic parts in this system.
AlexA64042 years ago
Thank you for the instructions. This is great info. One concern that I have is to make sure that the combination hinge and the mending plate are not too heavy for the actuator motors to cause them to fail in the long term? How does their weight compare to the original (plastic) door/hinge? I understand that, if the passenger side actuator motor fails, you will need to remove the dash to get to it, which is what we are trying to avoid in the first place.