Cold Air From the Glove Compartment of a Ford Explorer

If your Ford Explorer has suddenly started blowing freezing cold air from the glove compartment, here's why. There is a duct (or plenum, if you prefer) installed under your dashboard, behind the glove compartment, and the passenger side air bag. Inside this plenum is a swinging door controlled by a vacuum device that moves it from one side of this plenum to the other. You can see this door clearly in the second photo. When swung towards the rear of the vehicle, it allows cold air from outside the vehicle into the blower that distributes air to the rest of the vehicle's HVAC system. When swung towards the front of the vehicle, it allows cabin air into the blower, and blocks the freezing cold air.

Now, here's your problem. Your door has broken off, and fallen to the bottom of the plenum. The result is that now, this door is lying across the fan intake, and freezing cold air from outside your explorer in now screaming unhindered through the grilles on either side of the plenum, pressurizing your glove compartment and the underside of your dashboard. This also has the effect of turning your passenger into a giant blue icicle. I know, it happened to Mrs. Smitty about halfway through a 150 mile trip. 

Well, no problem. This plenum is available from your friendly local Ford dealer for somewhere in the neighborhood of $68.00, complete with swinging door, and vacuum actuator. Oh, wait. Did I mention that this cheap plastic box is buried under your dashboard in such a fashion that the only way to gain access to it is to remove the whole dashboard? Well, no problem, if you're willing to spend two days ripping apart the interior of your truck to replace this poorly engineered piece of cheap plastic crap with another identical poorly engineered piece of cheap plastic crap with exactly the same life expectancy, and the same failure mode. Or, you could leave it in the hands of your friendly local Ford dealer who will only require ten hours (estimated) as the the technicians there are well acquainted with the procedure. They said so. For a mere $800 (estimated parts and labor) you can have your truck working again.

Ford tough, my a$$.

Or, you can do what I did. Before writing this post, I purchased the failed plenum and door assembly for the purpose of making clear photos. It is not necessary to buy a new duct assembly, or remove your old one. The procedure I describe here can be done with the duct in the car. It helps to be manually adroit, and have a spine like a slinky, but you don't have to to remove and replace your duct. You only have to remove the glove compartment door, a vacuum reservoir, and the cabin blower motor.

 All of the work I'm about to describe takes place directly below and in front of the passenger side air bag. Nothing I describe doing should cause the airbag to go off, but it's prudent to disarm the air bag before continuing. If you've read this far you're already screwed, and don't need the additional expense of replacing an airbag.

Remove the glove box. It swings completely down to the floor if you press in on the rear corners of the box. Three screws hold it onto the dashboard. Behind it you will see the blower motor down near the floor. Remove the blower motor. It's held in with three screws. You may have to remove a vacuum reservoir first. It looks something like a giant black suppository (which is pretty representative of this whole episode). Disconnect the vacuum line connected to it and move it out of your way. With the blower removed you can lie on your back, squirm under the dash, and look up into the hole where the blower was. Or, use a small mirror and flashlight. You will see the door in question lying on top of the hole where air should enter the blower.  If not, you have a different problem.

Use a pocket knife to cut the plastic screen at the bottom of the plenum out of the way. You can live without it. This screen is visible in the second photo.This will allow you to reach inside, and push the door up where it belongs. It may have turned over when it fell, and you may have to turn it over for it to fit. I did.

Now you need a way to secure the door such that it seals the cabin side of the plenum, and allows outside air into the blower, permanently. I used a piece of aluminum to fabricate a bracket for this purpose. As I had  purchased a replacement plenum from my local Ford dealer, and could use it as a model, I had no problem shaping a bracket to fit the inside of the duct, and secure the door. I have traced the bracket as you can see in the photo. If anyone out there should want the bracket's dimensions, contact me through the comments, and I'll publish dimensions.The next photo shows the bracket placed as it will be installed inside the truck. It will be held by the two sheet metal screws

I also made a template to enable me to locate holes for bracket screws outside the plenum. You can drill the holes with any electric drill by access provided by the cavity in the dash board where the glove box used to be. Install the bracket once you have drilled holes. This requires you to palm the bracket in one hand and use the fingers of the same hand to position the door, then place and hold the bracket while driving the screws with the other hand. I did it. So can you. It helps if someone stands by to hand you tools and screws. The next two photos show the template in place prior to marking and drilling holes for the screws, and the screws in place, securing bracket and door.

Reassemble your vehicle. What you will have is a permanent repair takes a couple hours, costs you almost nothing and deprives Ford of any additional revenue. I call that a win-win. Your truck's HVAC will work as before, with the exception that the door if fixed in place. This means that the door will always be in the "vent" position and will allow air into the cabin interior, through the blower. If the blower is off, very little air will enter the cabin, even going down the road at 70 mph. It the blower is on, everything will work as before. The only other time the door would have moved is the Max Air setting, (or recirculate). Your AC will still cool the interior, only with vented air instead of recirculated air. If your Exploder is equipped with front and rear AC, you'll not notice the difference, unless you live someplace like Arizona.

The reason this door breaks and falls is that the crank on the driver side of the plenum is loosely attached to the door with what appears to my untrained eye to be nothing more than an ultrasonic weld. Now, if the geniuses at Ford had used a screw to secure this crank, like the screws they used to fasten the two halves of the plenum together, then this failure most likely would never have happened to my vehicle, or judging from what I'm able to find on the internet, many others. It seems to me that if you're going to bury a component that operates every single time a customer drives his truck, sometimes multiple times, in a location where it takes something like ten hours to get at it, you would take pains to see that it's reliable, and not likely to fail for the life of the vehicle, instead of depending on a cheesy ultrasonic weld, or glue, or whatever.

Unless of course, your goal is to cost your customer a fortune, and drive him to purchase a vehicle from another manufacturer. That sort of thing does happen. The last photo is Mrs. Smitty's new Camry. She likes it a lot. I like it because it doesn't have Ford duct assembly 12LZ-18B259-AC under the dash.