Wednesday, February 20, 2008

Expedition Blend Door

Ok, I have already touched on it, but here is the quick and short attempt...
Almost every Ford made after sometime in the 90's has a fatal flaw. The little plastic door that mixes hot and cold air for the heat/AC is run by a crappy little servo motor. Instead of the tried and true cable (and usually a metal door) you have this awful remote motor. And pretty much all of them break. Thanks Ford.
The fix is awful. You have to rip the entire dash apart. And when you do, and call the parts store, they tell you "we dont sell that." It turns out, the junkyards wont sell them either. I guess a $10 part isnt worth their 8 hours of pulling the part.
Here comes Bubba engineering.
  1. Steering wheel dropped, dash completely ripped out.

  2. The magical blend door. Enjoy its spendor. It clearly is worth $350 in parts alone. It is beautiful and oddly arousing.
  3. And here is the defective end. You cannot expect this to be heated to 200 degrees in the summer then be turned 5 degrees past its design limits without eventually breaking. Get this Ford?
  4. So I reached into the air handler box and fished out the bits and pieces. This should be enough to glue together to approximate the size/shape of the new part.
  5. Here it is all glued together. I was missing one piece, but its the general size/shape I was trying to figure out.
  6. I got an approximately sized brass fitting and brass thrust washer. I pressed the thrust washer onto the fitting. This is approximately the same size as the end bit. The only gotcha here is that the air handler really needs to be taken apart (which means pulling the heater core and the AC evaporator. No thank you.) I decide I will notch the brim of the tophat after I solder it together.
  7. I cut back the excess of the bottom of the door to make the tophat fit in.
  8. And here is my finished bit of wonderment. I took a 5/8 copper pipe and cut long grooves in it to match the spine of the blend door. I then soldered the tophat into the butt end of it. Even though I clearly marked which groove was the door side and which was the hinge side, I still soldered the cutout part of the tophat in bassackwards. I ended up soldering it 4 times before I was done. I vaguely remember from my plumbing days that brass was a little trickier to work with than copper. I think it not only requires more heat, but more finesse and more evenly distributed heat. My solders are really ugly, but they dont have to hold water. They only have to stay together. I press on.
  9. The completed brace next to its new home.
  10. I slid the brace in place and bolted it down for good measure. It was pretty darn tight before I bolted it, but why stop at halfway when you can over engineer?
  11. I drilled a hole in the blend door servo motor and inserted a little pin.
  12. Here is the little beauty with a slot in its bottom sitting on the motor, happy as a clam.
  13. On my first installation attempt I found that there was, in fact, no way to get the top and bottom pins of the hinge in place without taking out the air handler box -- further dismantling the dash and draining the heater core and AC evaporator. So I cut the top plastic pin off flush and replaced it with a screw. Is there anything a drywall screw wont fix?
  14. And now for the money shot. Here you see the air handler box pried halfway open and the door is installed. It is "closed" or cold -- capping off air through the heater core.
  15. Another angle of the money shot with the camera held inside the air handler box. You might notice I had to remove the little pin and nuts on the shaft. They interfered with the hinge operation on the inside of the door.
  16. I managed to close off the air handler and with much MUCH MUCH finagling I got the servo bolted on the underside of the box.
  17. ...and at this point I realize a couple of things. First, a mechanic had told me a long time ago that the door warps with time and this was part of the problem. The door closes at the bottom fully, but not at the top (on full cold). This explains why my AC hasnt been supercold in a long while (before it broke entirely). Second, my actuator motor was just tired and worn out. It works. Sort of. Most of the time. I am sure pushing on a broken door had a lot to do with this. So I begrudgingly buy another motor for about $65.
  18. ...and the Bubbagineering department starts again on the door. Here is the before pictures. Hot...
    ...and cold
    So I beefed up the foam...
    and now... Hot...
    ...and cold
  19. Ambient temperature
  20. Heater +50 degrees. Sweet.
  21. AC -21 degrees. Not awful.
  22. Tada...

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