Followed Steve's advice, replaced blend door actuator, fixed problem. (
Here is my report:
The situation
1997 Explorer Limited, AWD. Air conditioner failed with a clicking noise. Blew hot, then cold. Noise sounds like somebody tapping a hammer behind dashboard.Good mechanic at neighborhood gas station said he would have to remove dashboard, big labor job, $1200. Too bad, he said because the part is cheap. Has seen this a lot of Ford cars and Explorers. No way around it.
Then I found the thread cited above. Opened glove box, pushed sides together so it would swing all the way down, revealing blend door actuator. See bundle of wires going into white actuator box. Unclip the wire bundle to stop the clicking. We are going to remove this actuator and replace it. Yes, they said it can;t be done without removing the dashboard. But they were wrong.
Before proceeding
Make sure you have or had clicking sound when operating Heat/cooling system. The clicking sound means only the actuator is broken. The actuator is a four-inch square plastic mechanism containing plastic gears. It's job is to mechanically move a "blend door" to achieve the cabin temperature you have selected.
The blend door is just a flap, or door, inside the system that splits air flow to the cabin vents. If you choose max air, it closes off outside air and you get 100 percent AC. If you choose 70 degrees, and it is zero degrees outside, the blend door directs most of the heater output to you, allowing in a little outside air to keep it at 70. If you choose a cabin temp of 80, it lets in less outside air. In other words, the blend door "blends" the air.
There is a shaft, or plenum, between the blend door and the actuator on top. If that shaft is broken, Google this: Ford Explorer Blend Door Fix by Jeff Frank. If you didn;t hear clicking, maybe that;s the problem.
But if you have a clicking noise, the plenum is probably OK, and just the actuator is bad.
Removing the actuator
Start with several hours and a good mood. You'll need both. You may get discouraged. Hey, if I did it, you can. And you are going to save $1400.
The actuator is white. Held in place by three 5/16th nut-screws (I.e., screw with a nut head). The two in the front you can see. Feel behind the actuator, in the middle and slightly down, for the third screw.
Not much room for your hand. You cant see much. This will be done by feel. After a while you will develop a mental picture of surprising clarity of this accursed actuator box.
Because there is no room to work in there, you need the smallest ratchet wrench available. I had a 1/8-inch drive ratchet handle with
5/16 socket. Also have on hand a 5/16 spanner (simple double-ended tiny wrench).Remove the two front screws. It's not too hard.
The third screw is the tough one. Before starting, duct-tape a piece of string to your socket. Tape another piece of string to the ratchet wrench handle. Also put a strong on the spanner. Now when you drop them back there, you can fish them out.
The socket wrench will not fit easily on the third screw because there is no vertical room. You must get fingers in there with both hands, elevate the wrench horizontal, fit the socket on the head, and try to turn it. All at the same time. You will only have room to move the handle one "click" of the ratchet. This turns the screw about 1/8 revolution. All this is at fingertip length. It seems impossible. Don't give up.
When discouraged, simply feel again the work area. Study with a flashlight and a dental mirror. Get to know that area. At first, success will be stinkin' click of the ratchet! It took me two hours to get that screw off. Yes, its an uncomfortable position. Rest your head on the dashboard, and learn to see the world through the ends of your fingers. This is the $1400-dollar screw.
Success!
Now just lift or gently pry up the actuator and out it comes. You'll seen the plastic shaft that operates the blend door. It sticks down, which is why you have to lift the actuator before you pull it out.
Open the actuator body (you can break the tabs) and you'll see several nylon gears and bushings. Take them apart and look carefully. If you find some gears stripped, you know why it was clicking. Only two tiny gears on mine were stripped, on the smallest cog-wheel. You want to find stripped gears, because that proves the actuator is bad (and that's what caused the clicking sound as the gears meshed wrong).
The actuator has a number written on it. Mine said: F57H-19E694-BA. EATC (meaning electronic, not manual heater control.) This, I found out, is the "Service Number," not the part number. My part number turned out to be F77Z-19E616-BA.
Call a ford dealer (or internet supply house) and order a new actuator ($83.26 as of Feb, 2007) . My ford dealer's computer showed the part in stock 20 miles away, so I drove and picked it up. I was also told that is part will be discontinued fairly soon. (If so, you can still find it on the internet, or at worst from a junkyard).
Take the old actuator with you so you can make sure the new one looks exactly the same and says EATC. The new part number will probably be slightly different, but I was told this is "always the case." Still, I would insist on an explanation, since you must have the right part for your model year.
Since you are now far, far too familiar with uninstalling the actuator, reinstalling it is simple.
Just FORGET THE THIRD SCREW. You can't put it back anyway, probably.
At first, I could not get the D-shaped nylon plenum shaft (sticks out the bottom of the actuator) to fit into its female hole. The shaft must be aligned just the way the D-shaped plenum hole is, or they won't insert. Scope out the current position of the hole with your dental mirror and try to get them the same.
Don't try to rotate your new actuator shaft by hand, or with a tool. To rotate it, just hook up the wires, turn on the car, and operate your temperature control, which turns the shaft. Match the positions so the actuator shaft will fit into the plenum hole.
What I eventually wound up doing was to hold the actuator in place, and keep changing the temperature setting up and down until they two shafts momentarily hit the point of alignment and slipped together. You'll know when it happens, the actuator snugs down nicely.
The two front screws are pretty easy to reinstall. Dont overtighten, they are just bedded in plastic.
That's all there is to it. Congratulations! If I can answer a question, you can contact me through
Regards, Christian