Blend door actuator failure is a common problem in Ford Taurus SHO's, as well as other Fords. There is no way to get to the blend door other than by pulling the whole dash away from the firewall. Common symptoms of a blend door failure consist of a "thumping" in the dash when the heater is on, only being able to get hot air from the vents, and a code of 02 from the electronic climate control self-test. To perform the self test, make sure the engine is at operating temperature. First press both the OFF and FLOOR buttons and then press the AUTOMATIC button within 2 seconds. The test will run for up to 20 seconds and then display the codes, if there are any. You may also want to consider replacing the heater core and/or vacuum line while you are doing this (see NOTES for steps 19 &21). I did not, so these are not covered here.
This is based upon pictures I took and what I remember from when I replaced the BDA in my 1995 MTX SHO. Hopefully everything is correct, email me at: redline21@hotmail.com with any additions/corrections. You may notice in some of the pictures that I did things in a different order than I have them listed here or that I did things that I did not list at all here. This is due to the "learn as you go" factor. I have put the steps in an order that is hopefully the fastest and easiest. I actually did this job twice on the same car. The first time it took me about 8 hours and the second time it only took me about 5 hours or less. Hopefully with these instructions will help you speed up the process.*
Other than sockets, screwdrivers, and pliers, there are a few tools you may need that you may or may not have handy:
1. Start with the center console. Remove the shift knob by unscrewing it counter-clockwise. (If you have an ATX you will have to figure this step out on your own, sorry). Then pull out the rubber piece of the cup holder. Remove the screw found underneath. It takes a torx head or a socket.
2. Remove the center console. Other than the one screw, it is held only by some clips. You can see where they are all by the picture below. Pop them loose and slide the boot up over the gearshift. You will also need to disconnect the plug for the cigarette lighter.
3. Before you can remove the rest of the center console, you will need to remove the stereo to access some bolts holding the front of the console. If you have a factory radio, you will need the special Ford tool to remove it. I freaked out at first because I had no idea how remove the radio. Fortunately, there was one set of tools left at Schucks for about $5. Stick them into the holes on each side of your radio. Push them all the way in, then push the ends closest to you out, away from each other. While pushing the ends away from each other, pull the them towards you and the radio should slide right out.
4. Unplug the radio wires as you pull the units out. If you are worried about mixing wires up, you can zip-tie the ones for each unit together.
5. Once you get the radio out, there are two nuts and one screw that need to be pulled. The first pictures shows the two nuts at the bottom that can be removed with a socket. The screw in the second picture is located behind the wires in the first picture. It is removed with either a socket or torx head.
6. Now you can go back to removing the center console. There are two nuts at the front under the radio that have to be pulled, three screws in the middle behind the gearshift, and four screws inside the storage bin in the console underneath the foam padding. You will also need to disconnect the electrical connection in the second picture (I think this is the only one). With these removed you should be able to pull out the center console There is a metal bracket that was held by the nuts in the first picture that can be a bit of a pain but with some wiggling it should all come apart.
7. Now you will need to remove one more screw from under the radio that was not accessible before. Remove it from below. When I reinstalled things I left it out, because I did not see a reason for it and have had no problems with squeaks or looseness or anything. There are already two bolts holding things in place so I'm not sure what the point of it was.
8. Remove the large metal trim piece below the steering wheel. It is held in place by four torx head screws.
9. Remove the metal brace that sits below the steering column. It is held by a bolt at each end.
10. Remove the bolt down by the gas pedal.
11. Now you need to drop the whole steering column. There are eight nuts on four bolts that have to be removed. The first four nuts hold a metal plate on. The second four hold the actual column on. You will need a deep well socket for these. I think there may have been a slight difference between the top four and the bottom four nuts so keep them separated. After you pull all eight nuts, set the column carefully on the floor.
12. Remove the two screws in the dash on either side of where the column was and the one bolt that was hidden behind the column.
13. Remove the driver and passenger kick panels. They are each held in place by two phillips screws.
14. Remove the two dash bolts found behind the kick panels.
15. Remove the driver and passenger side a-pillars trim pieces. They are held on by about four metal clips. The clips were so tight on mine that most of them broke the plastic when I pulled them off. I super-glued them back on with some really good glue and pinched the metal clips down a bit so they aren't quite so tight and they go on and off fine now.
16. Use a screwdriver to popup each of the three trim pieces on the top of the dash under the windshield. Remove all three dash bolts found under them. Unless you are lucky enough to have no windshield in your car, you will need several long ratchet extensions for these or else you will be turning them all day because there is very little room to work between the windshield and the top of the dash.
17. The dash "should" now be free and pull away several inches from the firewall. It may be helpful to have someone pull on the other side at this point and you may have to lift up and out a bit to get it free. The only thing holding it is the speedometer cable. Pull it as far away as you can, and then reach over the top of the dash and in from behind and feel for the plastic clip at the end of the speedometer cable. As you can see in the picture, there is a clip on one side that holds it. Squeeze on the clip and it should pop free easily. It is much easier to access the cable this way than from below, where you would need to be double jointed and have hobbit fingers (no offense intended to hobbits).
18. Pull the dash free the rest of the way and pull it out from the firewall as far as possible. Be careful of the shifter as the dash will want to rest against this and it may scrape your dash or smash you heater vent - as it did in my case :(. There should be no other hoses or wires that need disconnected unless you are doing a heater core, in which case I will wish you good luck. You should now be able to easily locate the BDA
19. Unplug the electrical connection. The BDA is held in place by a bracket. There are three posts that clip the BDA onto the bracket and the bracket is held in place by three screws. For starters, stick a screwdriver underneath the BDA and pry it upwards off of the bracket. It should pop up off of the tabs fairly easily. Then carefully pull the BDA stem up out off the hole in the top of the blend door. Be careful or you may crack the top of the blend door sleeve (like I did) and have to repair it. If you crack the blend door sleeve, I will show you how to fix it later on after you install the new BDA. Wiggle the BDA around and pull it out to the left. Apparently there are two different types of BDAs/brackets. If you are lucky, your old bracket will work for your new BDA and you can toss the extra new bracket. If you are unlucky you will need to replace the old bracket with the new one as well. If you have to replace the BDA bracket, go to step 20. Otherwise, skip to step 21.
NOTE: It is recommended that you replace the heater core at this point if it has not been done in a long time or if it is giving you trouble. I did not do this, because I didn't have the tools to disconnect the A/C lines from the heater core (and because I'm poor and lazy!). Also, if you live in a climate that is fairly warm in the winter and you don't really need your heat, it is much easier to do a heater core bypass than to replace it.
20. I was lucky and did not have to replace the bracket, but I can still probably give you some pointers to doing it. Make sure you remove the BDA from the bracket first. The front two screws are not as hard to get at but the back one looks very difficult to me. Credit for this goes to Rockledge on SHOForum, as I got the idea from him. I would recommend breaking the old bracket around the back screw if you can to get it out of the way and give yourself more room. Then unscrew the back screw partially, but not all the way. On the new bracket, clip the back part off that would go behind the screw so that it makes a U-shape around the screw instead of a full circle and you can slide the new bracket into place underneath the back screw without removing it. Then tighten the screw back down and put the other two back in. As I said, I have not actually done this, but hopefully it will work for you.
21. Now you should be able to slide the new BDA back into place in a similar manner to the way it came out. One trouble spot to watch is the small thin black vacuum line that comes from the right and runs out through the firewall behind the BDA. Make sure that it stays behind the bracket. If it gets between the bracket and the new BDA, the BDA will not slide down over the clips like it should. Other than that, the BDA should go right into place. Don't forget to plug in the electrical connection! ;) If the blend door sleeve got cracked in the process of removal and installation, or if it was that way to begin with, go to step 22 to see how to fix it. Otherwise, skip to step 23.
NOTE: Speaking of the vacuum line, this would be a great time to replace it if it is worn out or broken. The most common point of failure is in the engine bay right where it comes through the firewall (beside the heater core hoses) and bends towards the passenger side of the care. It can get brittle and break or get a hole. The most typical symptom of a vacuum line problem is being able to get air only from the defrost vent. A vacuum motor controls the door that tells the air which vent to go through so if you are only getting air through the defrost the vacuum motor or line is bad.
22. If you cracked the sleeve for the BDA stem, it is fairly easy to fix. If you completely broke it, then this may not help much and you are on your own. Credit for this fix goes to Rockledge on SHOForum.com as it was his idea originally and I copied it to fix mine. First, with the new BDA in place, take a zip-tie and put it around the sleeve. Suck it up good and tight and make sure that the "head" of the zip-tie is in a place that will not interfere with the back and forth rotation of the blend door. Make sure you clip the tail off of the zip-tie. Then take some super glue and put it all around the sleeve right above the zip-tie to glue the crack in the sleeve together and to glue the zip-tie to the sleeve. Make sure you are careful with the superglue. You don't want to glue the whole sleeve to the housing and freeze it in place! Also, give it plenty of time to dry.
23. Now that the BDA is in place, you may want to test it just to make sure it works before you put everything back together. To test it all, you will need to ground the dash to the firewall. The easiest way to do this is with a spare piece of wire. Use the wire to ground from one of the dash holes to one of the firewall holes. Probably the easiest and best one is the one you pulled the bolt out off in step #12. It worked good for me anyway. Make sure that your blend door moves back and forth like it should when you switch your heater temperature from hot to cold. Testing is optional thought, so if everything looks good and you feel confident in your work, skip it.
24. Now you can start putting everything back together. Make sure none of your hoses or vacuum lines have come disconnected. Also, wait to install the speedo cable until after the dash is back in place. Installation is almost the reverse of removal except for a few small things. First of all, I HIGHLY recommend having someone handy to help reinstall the dash. It is a real pain to try and lift it back up into place by yourself. I also cracked my dash in the process which really made me mad, because it never would have happened there had been someone helping me lift it back into place.
25. Don't try to reconnect the speedometer the same way you disconnected it. I found that it was actually easier to put the whole dash back into place and then reach up from underneath and push the speedo cable back into its socket. Just one of those weird things where removal and installation seem to be easier different ways. Everything else should be reverse of install. Good luck!
NOTE: The point of failure in my BDA was a gear in the assembly. The teeth on the gear were worn out so the motor was spinning but not turning anything.