So I know that the blend door actuators on our beloved 98 to 2011 Vics and MGM's fail all the time, on the EATC automatic units. I have two myself that have failed BDA's. The first one on my 2007 Sport failed before I got it, but all my diagnosis points towards the BDA either having failed or the armature having "come off" the swinging rod that flips the door. All the vacuum controls switch modes from vent to defrost to floor and back, fan works, a/c, temperature gauges all works.... the only thing it does is blow FULL HEAT all the time in every mode. But the BDA is not connected to vacuum tubes, it's all electronic That tells me that it is the BDA. Do you agree?

The second car was is my 2006 MGM which I picked up yesterday and they told me, "Hey, good news, the AC actually works, we topped it off and it's blowing cold." Got in it, it worked fine with no trace of an issue in any function. Blew ice cold from Fresno to Wendover, NV in fact so cold that when the sun went down, I turned it way up, to 72 degrees, and to normal AC and low fan. So basically I was turning it to a "middle" or warm position.

Then I woke up this morning for the second day's drive, flipped it to max a/c and 65 degrees, turned up the fan to get it back to cold for the desert drive and I immediately started to hear this plastic sounding click-clunk, click-clunk from the right center dash behind the radio... right where the BDA is. It repeated this clicking about 10 times, then stopped and the meanwhile the heat blows FULL HOT in all modes just as with the 2007 Sport. It did not come back. Blend door is stuck full open to heat, just as in the 2007.

You can tell that the EATC is working to try to cool but can't, when the temp was about 72 outside and I set the temp to 72 and pushed automatic, the EATC sensed air that was where it wanted to be and basically shut itself down, blowing only lightly.

So my question is this: when these BDA's fail, how do they fail? Does the armature pop off the rod? is there something in the door that gets them stuck and will cause a new one to get stuck and break again? Do the little gear teeth wear out, get brittle and break off, cause the gate not to swing? Is it an electronic burn-out issue?

Any thoughts would be welcome.

They overrun and the last tooth of the gear breaks off because it continues to try to move it even if at full stop.

My 97 Mark VIII had a similar issue, the arm would stop before the gear would, and break the last couple of teeth. At least with it you could reach up and manually select heat or AC, I had 2 zip ties ready for whichever mode I needed (even in middle of winter I didn't need heat, but on the rare occurrence I did I could reach up and move it in 2 seconds).

Both of the ones I removed from my 2000 Grand Marquis it was gear. However then one of the flaps fell off (I think for air selector, don't remember) and the AC lost its charge and I gave up.

Sometimes if I ran the self test enough it would be able to grab and move the blend door to the mode I needed it in, but then the EATC would eventually start blending it and eventually it would go back into failure mode.

Well, that sounds like what mine was doing when it broke on full stop heat. I've reached in under the glove box and can feel the gate full open to heat, tried to manually move it but the it is firmly wedge in that heat position. Somebody said that if I turn the unit on and set it to cold while running, I may be able to manually push the door to AC, but no go.

Gears inside BDA are nylon which ages and cracks over time. Sometimes the lubrication dries up which causes mechanical issues. Brass gears and stronger actautor motor would add about 20 bucks to the cost of a BDA and would have made the part bulletproof.

My experience is that the BDA failures stem from problems with the potentiometer that signals position of the door.

Over time, the potentiometer eventually gets covered in the grease that lubes the mechanical parts. This leads to a false position signal. With the position unknown or incorrect, the BDA ends up being driven beyond the physical limits of the door, stressing all of the plastic gears, stripping them out or cracking them. After that, it's game over.

I've completed my first blend door actuator swap in my 2006 MGM with success.

It was as beastly a fussy job as everyone says, I clocked in at a little over 3 1/2 hours, most of which was wasted time as I did not know what I was doing and I struggled with many dead ends. I watched all the youtube videos dealing with the job... and I mean ALL of them... about 20 in total, looking hoping searching for some secret trick that would shorten the agony or make the 3 hour job easier. In the end, I determined that NO single video available on Youtube has the right combination of advice and some are downright deceptive. I probably should make my own, but I'm not in that market. At best, I can provide the following tips for CVN guys should they need to embark on the same journey I undertook. My advice below will make sense to folks who have watched a few videos on this first. I've got another BDA replacement to do tomorrow, and I'll time myself this second time around, following my own advice, to see if I can do better now that I know what I'm doing.

1) Do not believe the guys who say you can go in through the glove compartment and remove one screw to move the door lever manually by hand to get manual AC or manual heat that you then have to move twice a year. This is a beastly awkward and difficult job that doesn't solve your problem and takes a long time to no useful end.

2) Resolve yourself to removing the front fascia, removing the airbag, removing the top dash fascia, removing the right side duct tubing, and removing the 3 screws holding the right side of the dash to the firewall, then propping the dash cracked open from the right with a twoxfour. Just do it, don't hestitate, just do it. You'll save countless minutes of fussing with hard to reach screws if you do all this right up front.

3) You will need a small 1/4 ratchet, 7mm, 8mm and 10mm sockets, a big screwdriver or pry bar, electric drill or power screw driver and these tools to save yourself a lot of knuckle scraping agony.



They cost $11 on ebay. You'll need the angled driver to remove and re-install the fussy screws holding the vent tube to the front dash (from behind) and you need the snake to snake down through the secret dash hole from the top to undo and redo the front left screw in the actuator.

3) When removing the vent tube behind the air bag, its okay if you crack the two clam shell pieces of the tube in half. It's just a vent tube and you can zip tie them shut again after you put them back in. It's much easier to re-install if you do this.

4) With the airbag out, the vent out, the right dash pried open, you now have enough room to work. Unplug all three of the electrical plugs you can see on the actuator and to the right of it that are in your way.

5) Remove the front right screw on top of the actuator with a 8mm socket and small ratchet. This comes out super easy. Next go after the front left screw by snaking the flex tube down through the access hole on the top dash and connected to your drill on one end and the same 8mm socket that you seat on the screw with your right hand, undo it.

6) With two screws out, take a big screwdriver, crowbar or other long pry bar, wedge it under the actuator and break it upwards. Only one screw is holding it in at the back right and it will break easily. The fourth mount ring at the back left isn't used, there's nothing holding the back left. Just break it, you won't need it. When it's broken pull the dead actuator out.

7) With the actuator out, loosen the rear right screw a couple of turns, and clear any residual plastic pieces from its neck. Re-insert the front left screw into its hole with your fingers and finger tighten it down as far as you can go. These two screws provide posts against which you're going to seat the new actuator.

8) Trim the new actuator's ring holes as indicate below with a dremel or other precision cutting tool. You may even be able to do it with a box-cutter, the plastic isn't very strong. You're just trying to create slots that you will feed around the screw posts in the back right and front left.



Some guys struggle to remove all the screws, then struggle to tighten them all again. This isn't necessary. And if the BDA breaks again, as they are want to do, it'll be easier to remove the next time. These things don't break because they're loosely mounted, they break inside.

9) Here's the part NONE of the videos tell you. BEFORE you screw down the BDA against its posts, you will need to re-connect your three HVAC plugs that you've disconnected and plug in the square white plug into the top of the BDA while it's just sitting loose in the void behind the dash. Then you run a EATC self test that puts the new actuator through its motions.

You do this for two reasons, one to see that the new BDA passes the test and moves, and two, to move the little blend door lever shroud on the bottom of the BDA to a more neutral "middle-arc" position between all the way closed and all the way open. Odds are your new BDA will come with its gate lever slammed all the way over to heat side, even beyond the natural travel reach of the blend door lever. You can't mount it like this. DO NOT TRY TO MANUALLY MOVE THAT lever shroud or YOU'LL BREAK THE GEAR TEETH inside the unit. Run the self-test and let the system move the arm to the middle, then you can remount it against the two posts.

10) Insert the BDA, getting the shroud over the BD arm, and seating the two cut slots under the screw tops in the back right (first) and then swing it over to seat the front left (second). Try to re-tighten the back right screw the few turns you loosened it if you can (but you won't be able to). Insert the front right screw and tighten it down. Then go back down through the secret dash top access hole with your snake thingy and the 8mm socket, with the electric driver and re tighten the front left screw all the way down. Trust me, it will be snug.

It's in, now re-assemble the dash in the reverse order you cracked it open. Test it, you're good to go.

I agree that there's no good videos on YouTube.
I myself prefer the dash removal method, and doing so the job only takes me an hour and a half.
If you're on Facebook, I have a complete guide with photos here:
Heater Core/Blend Door Actuator Replacement Guide
https://www.facebook.com/groups/crownvictoriap71p7b/permalink/258332852708178/

Testing the BDA is very good advice. Bit do NOT test the new one without having it installed on the HVAC box. If it's not attached to the door it will over travel and Break.

Sadly that's a private group that you have to join to see, so I couldn't see it. Having done one now myself, I can't see why it's necessary to remove the whole dash when merely prying open the right side does give you all the access you need to complete the job.

Here's the problem I had with attaching the BDA to the box before testing... I couldn't do it. Both of my new BDA's came with the lever shroud in the green position out of the box, beyond the normal travel range of the actuators when in use. The BDA shroud would not fit over the BD door lever in a mounted position unless it was moved to at least the "heat" position.



The only way to move it was to force it, or get the gears to work themselves in test mode coming to rest about half way between heat and cool.

The technique is simply pulling the right side of dash out.
You remove most of the mounting bolts (about 10 bolts total), and swing passenger side out.
Airbag, glovebox, steering column all stay attached to the dash.
Dash swings far enough that it can be set on the passenger seat.

Hmmm, sounds like overkill, but I'd love to see the video for the next one I do. Prying loose the right side of the dash only required removing 2 7mm screws and 1 10mm nut from the top and right, then you can wedge it open enough, holding it open with a 2x4, to get the access you need.

My second effort clocked in at 2 hours and 10 minutes, with about 20 minutes lost in a frustrated effort to re-seat the new actuator that just wouldn't mount whereas the this step was easy-peasy with the first one I did.

It turned out that there was an actual post in the back left position whereas on the GMG that was only 1 year older, there was no post in this position, it was blank. So as I tried to seat the new actuator, the back left mounting ring kept bumping against this post and it wouldn't seat. Once I noticed the post and slid over it, I got the thing seated the first time.

I found one more efficiency this run through which was to remove the glove compartment via it's two easy-reach 7mm screws. This allows even better access to the mounting screws holding the vent tube to the back of the dash, which are buggers to get otherwise, and it allows the vent to be removed and re-inserted from below without cracking its clamshell in half. This second time I also did not notch the front left ring bracket on the BDA, I simply threaded the screw through it from above instead and it was easy to tighten with the snake tool through the top access port.

After I was done I cracked open one of my two old "failed" BDA's to find no nylon gears stripped or cracked, but grease EVERYWHERE, including all over the potentiometer strip.

As 2011LX indicated, I think this is the reason it failed, because the slopped grease kept it from sensing it's own position and then it wouldn't open the gate again. I think that I probably could have removed the gears (which slide right off), cleaned the potentiometer strip with alcohol, daubed up the excess grease, reseated the gears to a neutral middle position, and then glued the plastic clamshell shut again and it would have worked just fine. I could have tested it with the same EATC self-test I used on the new ones before hard mount, and determined if I'd done the trick or not.

I didn't do this, but I think it would have worked.

Anyway, now I have automatic heat and cool in both cars. $40 in parts and 5 3/4 hrs of work. But I'm pretty happy. Now I get to enjoy the premium stereo in the 2007 Sport with no ambient wind noise and it is pretty sweet.

All I've got left to do on that car is leather seat reconditioning and the Lincoln steering wheel swap and it will be as upgraded as I can get it.

I just completed a BDA replacement on a 2011 LX. Failure mode was like the OP, blew hot all the time. Replacement BDA completely fixed the problem (what a job that was!). I tore the old BDA open, interior look perfect, motor and gears all straight neat. I assume, it was the position potentiometer that failed.

On the bright side, I was also able to replace the heater core while I was in there.

This is a job where you will get to KNOW your CV better. LOLOL...

C'mon spill the deets! What method did you use, and how much time? Sounds like you took the dash all the way off to get at the core.

What about the grease in the BDA, did it look to be smeared everywhere, including on the Potentiometer strip?

Yes, I removed the steering column and the entire dash assembly. The Ford Workshop Manual was indispensable, BTW. The process took weeks, doing things in my spare time, waiting for parts, etc., so I don't have an exact time to replace the BDA. If I were to do it again, I think it could be accomplished in one day. I also replaced several plastic panels around the steering column and the shift lever boot, which was torn up.

The inside of the old BDA looked perfectly fine. White nylon worm gear on a little motor and all. I don't remember there being much grease in there, and it certainly wasn't smeared around. In fact, I thought my diagnosis was completely wrong at the time, and the whole project was a waste of time. However, the BDA replacement did, in fact, cure the issue. Automatic climate control now working as good as new.

Not much else to say. Having the dash out made the heater core change a piece of cake. I also took out the front seats and replaced the carpet (ACC after-market carpet), and lined the floor with Dynamat for good measure (I love that stuff).

Totally pleased with the outcome.

We always want feedback on your impressions of the ACC carpet, how'd it look, how'd it fit, did it lay flat etc.