09 CrewMax SR5-HVAC Partial Failure

Hi guys.

This issue started about a year ago. The best I recall, once I turned my truck off, I began to hear repetitive popping (like plastic gears slipping) from the servo area. That sound eventually went away, and I lost AC in my dash vents.

Starting at that time, I turn the truck off, and I can hear the servo (and maybe other HVAC gears) slowly seeking a resting position and cycling back, and then forth. And then turning back, and then forth again. The cycle repeats itself about 5-6 times over the time span of about 1 min. before coming to a rest.

I have ac/heat coming out of the defrost. I have residual air/heat coming out of the floor and vents. When selecting through the cabin air cycles, I hear a drop in the defrost pressure, but not a noticeable difference in the remaining air ports like vents and floor.

I replaced the entire servo unit part number 87106-0C070.

Before reassembling the unit, I plugged the two plugs in to observe the operation of the servo unit gears. They over rotated and the result was one slipping out of position (big tooth in small slot) . I popped the gear out and realigned, reassembled, and installed. My hopes were, once installed, the slots, arms, and receiving HVAC system, would limit the servo gears and prevent them from over rotating.

That's not been the case. I'm back to my original issue. Being somewhat familiar with diesel mechanics and troubleshooting, it makes me think there's a sending unit failure or limiting sensor or wire failure maybe? I say that because it did this over-rotation thing while the servo and the HVAC receiving unit were NOT married together, which is what I think I'm hearing now that its assembled. Preinstall. Confused? Me too.

 

This might help, one of the best videos I have seen on it. From what I remember alignment and setup on reinstallation is very important and really kind of a pain.

https://youtu.be/vDb0w_uol-8

 

Thank you. I watched that and was able to get everything assembled back together. But, what I've discovered is, replacing that part hasn't fixed the problem. I'm 90% sure everything was married up correctly though and i really appreciate your reply. What I'm wondering is if anyone else has any other leads as to what else it could be.

 

In my limited experience with the ac system I would lean toward somthing still not being aligned right or the servo motors not “clocked” correctly.

Did you make sure the ac control panel was set at the right setting when putting the servos on?

For example if the servos are moved to floor position when installed but the gears are set to front vents when assembling the clock of the servos would be off. This seems like the only way to get an over rotation.

Make sure the gears and servos (set by the control panel) are both in position 1 of the range when reassembling


Obviously the unit should not be cycling for a minute trying to reset or find where it should be. To me this is more evidence somthing is still not aligned properly

 

Thank you. I'll give that another go. I just need to know what Position 1 is, and how you found that? I'd love to have a book that tells me all this. All I have is my Chilton's. Breaking it all loose right now in the meantime. Thank you guys!

 

Here's what I'm seeing. Maybe one of you can spot something I'm doing wrong? Thx. I'll see if I can get the clip uploaded to YouTube and post the link also

 

This is the video of what I'm seeing? Is it supposed to do this when it's on? In his video, it moves when he turns his knobs, but only then. Mine moves right away. Frustrating

https://youtu.be/wB8xjLq4NMw

 

I am assuming you had to remove the servos from the old gear assembly and install in on the new one?

I would reset the gear to the face mode. Remove the servos. Turn the key on, the servos will go to spinning but not move the gears since they are separated.

Let the servos do whatever until they stop. Then start moving the dial on the controller and verify the servos turn one step for each movement of the dial.

Then work the dial all the way back to face watching the servo move all the way back to the face setting.

Then with the key still on and the servo still in the exact position I would reinstall the servo on the gear housing. You will now know the servo is to face as you watch it move with the dial and the gears will have already been pre adjusted to face before you started all this.

Then test to see if it still does the same thing.

This process will “reclock” the servo position on the gear assembly.

I think there are two servos, any chance you got the on backwards. You should eventually see one that shows consist movement with the dial as you move from face to floor to defrost when you have them unhooked from the gear assembly

 

I order an entire new unit with servos pre installed from factory. I definitely think that'd be a great idea if I had swapped servos though. Good thinking! I've taken the larger if the two gears out, turned the AC on and got the smaller to present the large tooth. I reinstalled the larger gear to match big tooth big valley, and cycled thru the air controls. For WHATEVER reason, the wheels turned the correct way and did not overrotate. I'm gonna try to install the unit now and see what happens. If this doesn't work, I have a tundra for sale for 1 dollar if anyone needs a project lol

 

$1.50 Bob!

Hopefully you got it reset to where it is happy. Maybe Toyota sent you one not perfectly synced up from new. Wouldn’t be the most shocking thing I have heard today.

Let us know if it’s now working.

 

Double it $3.oo! lol

I was looking at this for hints about how to get to the center section switches below the HVAC dials. Mine has bench seat, column shift.

Figured I'd place my bid though!

 

Ok, so I removed my servo sub assembly damper (87106-0C070) again to align/retime the gears. When I did that, a plastic arm fell off the (main unit??) So, now I need to find out what the servo sub assembly attaches to in the dash. I've circled the location the arm broke from. I e also attached a diagram of the part the arm attaches to. It doesn't have its own part designation number and I have no idea what it's called so i can start figuring out HTH to start repairing or replacing the broken arm or entire unit. Fml‍♂️