06 Limited - heat not blowing on floor

Diagram I did for someone else with mode damper issues:

robburns76 said:

it was the upper servo. only had to remove the drivers side dash panel and metal support to get to it. Took a bit to get the pins lined up right (must not have lined them up right when i replaced it.). Followed a tutorial on the Tundra forum (basically set it to floor, crank the fan to high, move the 3 valves to the right spot, then put the servo in place) and that worked well. Thanks for the help!

Click to expand...

This is exactly what I did when replacing the mode damper servo. My first attempt did not quite work as the pins were not correct. Air blew in the wrong directions and I got a code 43 on the diagnosis.

The best way for me to reach it was to remove the under dash driver's side trim, which requires disconnecting all the switches and, to make it easier, the hood latch cable. To reach the left most lower bolt remove the driver's side kick plate. Watch the clips! The metal dash brace has about 4 more bolts. Remove it and the black foot vent. It is held it place by a black plastic "pin" on the left and merely inserts into the heater. This should free up enough room to lay on your back and reach the 3 screws. A magnetic screwdriver will make the 2 harder to reach ones easier to get to.

I modified this and paste it here- It worked well.


In order to get the Mode Damper Servo installed with pins in the correct orientation do the following.

1. Plug the power connector into the servo with it loose and not installed.

2. Turn the ignition on and manually selected "floor" with the mode button on the HVAC panel. The servo should rotate to a pre-determined "floor" position . Disconnect the power from the servo.

3. Manually turned on the blower to the max speed. There are three (3) pins at issue which must be aligned. One is black and by the firewall, a second is on a white flexible arm assembly and the third a short white arm up high. Hard to see. Adjust the 3 until all air is directed to the floor vents. With the blower on the high setting, the visible flap stays into a closed position by its self.

4. Laying with my back on the floor and my head near the brake pedal, I very,very carefully set the servo assembly bracket alignment holes on the allignment pins on the box. The cam slots/tracks matched up perfectly with the pins on the flap arms and then I installed the screws that hold the servo assembly to the box.

5. Reconnect power to the servo and test all modes. You should see the arms move as the vents are changed. If OK, put rest of the dash back together.

Howdy All... 2007 Limited. 160,000 miles. I had the notorious faint clicking under the dash and all “mode” settings sent air through the dash vents.

I just got finished washing my hands after a job well done, with all the thanks to all of you here with these great instructions. I’m posting this to two different but seemingly the same threads on the same problem so forgive me if this is not appropriate.

What a pain in the ass this job was! I'll be 50 next month and I'm not sure how my back is going to feel tomorrow but the job is done and I'm one beer in.

A couple of quick things that I can mention that can perhaps shorten your trip. I'm not sure if you guys got a really special version of the Sienna where you're able to easily see high enough and through all the wires and riff-raff to get to see the aforementioned "windows" for the blend door pegs to fit in. No doing on mine; not even close to being able to get a visual on the pins in the cover. The servo box is too high and back to get your head in there. (I don’t have an abnormally big head). Especially with the 3" wide vertical steel support bracket with two 10mm fasteners on top which obscure the right half of the whole unit. I did not remove this! It looked too involved.

The previous instructions for removal of knee panel (and disconnecting the hood release) and left foot panel by the emergency brake are good. I disconnected all switches from the knee panel so I could totally remove it. This took much time as there are many different types of squeeze connectors for the electric mirrors, rear window vents, shut offs for the electric tailgate and side doors, the tire pressure reset button (all on the left of the steering wheel) and last the traction control cut off on the right. The steel bracket with the four 10mm screws is obvious enough.

What I needed to do which wasn’t mentioned previously was to remove the black blown plastic which channels the hot air to the driver foot well. It made all the difference in the world for access.

Removing the bracket and actuator: Snub nose Phillips for the bottom left screw, 10” Phillips for the top (get up and over all the brake pedal hardware) and a medium length Phillips for the bottom right screw.

Taking the mechanism off and out toward the firewall worked for me.

As for the actual gearing and motor bits, I lucked out. I got my old unit working again. One part that left me on my own as not being mentioned was how to remove the housing off the metal bracket. I inserted a wide blade screw driver between the housing and bracket and a bit of twisting persuasion and they came apart. I then used a sharpie marker to trace the profile of the black gear box around the steel bracket to be sure I got it back on correctly. In hindsight this is probably unnecessary as it probably only goes on one way.

After separating the two halves of the black gear box I cleaned off with alcohol what turn out to be a dirty coating of the factory lube that was on the contact disk leads on the largest gear. I then cleaned off the three copper leads mounted to the box which contact the large gear leads and also nudged them up a bit to make more solid contact with the large gear leads.

As mentioned in previous posts, I connected the 12V lead to the gearbox while it was not mounted, powered on the ignition and turned the fan on high, then used the “mode” button (this is an automatic climate control van) to the “floor” setting and turned the power off. This leaves the gearbox in the “floor” selection.

Before I set the gearbox to the “floor” position I went through all the air flow positions (defrost, dash, floor, mix) and it was then that I knew that I was in luck with my OEM gearbox as the motor did not “hunt” anymore. It chose a spot and stayed there for each setting.

Now is when the fun began!

My first attempt at mounting the actuator did not go well. I had no way to tell what position was what and hoped that as long as the four door arms (and pins) were under the cover I’d be good to go. It mounted up fine but when I powered up the ignition nothing moved. SHIT, now I have to go through the whole contortionist act again to disconnect the actuator. Not knowing where to go from there I then sat back to think. Flipping the floor door back and forth to see what was closed or open and same for the other three but there was nothing really to see.

Then I had an “ahah!” moment, which I hope was not outlined previously as I thought I’d read everything. With the actuator un-mounted, I powered up the ignition and turned the fan on high and manually worked the doors feeling the airflow to see which positions would give me all closed but the floor (which is where the actuator was set at). I scribbled down the positions which for my car are: Defroster = damper door arm to the right; Dash vents=damper door arm to the right and the food well: damper door arm UP.

When all was determined I powered the ignition down and CAREFULLY fit the actuator and bracket onto their locating holes, being sure not to upset any of the dampener arm settings. One last time of arm torturing, lactic acid buildup mayhem it was finally mounted and after connecting power realized the fruits of my labor.

Putting everything else back together took much less time than I expected and here I am now having a beer and telling you all about it.

I wonder what this would have cost to have someone else do it but I’m sure it would not be cheap. Yes, if I had to do it again, (I won’t) I could probably do it in half the time but in total it was about 3 hours.

Now I’m waiting for the motor to come in from Digi-Key to replace the actuator in my driver side power sliding door and our old “Marshmallow” (it’s pearlescent white) will be as good as new!

Thanks for all your help and I hope I added something useful here as you all have been priceless.