DIY: Replace Servo Sub-Assy

[sacra]

Just an update for anyone having a similar issue. After chasing this problem, replacing the cabin temperature sensor and the blend door servo. My next checklist item was the ac amplifier. I took my dash apart to check the connections and part number. I also followed the air temp sensor wiring from the sensor to the ac amplifier and found one of the wires had snapped off pretty far along.

Low and behold I reconnected it and problem solved.

The cabin air temperature sensor is on the driver side, right? Where is the ac amplifier located? Did you have to completely disassemble the center console (like you were changing the stereo head unit)?

I have an 06 with misbehaving air conditioning. If swapping the bottom air-mix servo doesn't fix the problem, maybe I'll take a look at the ac amplifier...

 

[Jenn1322]

Replaced both servo…but…

So I had the same issue of clicking and buzzing on my 04 TDR 4Runner. I tolerated it until I could no longer change the position of where the air comes from. Air only came out only on the face vents, but temp adjusted just fine. But I figured if I’m going to replace one, I might as well replace both while I’m in there since they are both moving parts with similar wear. I put the servos in and checked air before reassembling the glove box. Good news is the air does switch between, feet, face, and a mix of those and defrost. Bad news is there’s always air coming out of the defrost as well, no matter what position I switch it to. Less on some settings than others too? Not too worried for winter but with summer I’ll be fogging up my windshield with ac on it all the time. Is there something else I can double check or need to adjust before I reassemble the glove box.
Thanks in advance for any suggestions.

 

[hunterD1]

So I had the same issue of clicking and buzzing on my 04 TDR 4Runner. I tolerated it until I could no longer change the position of where the air comes from. Air only came out only on the face vents, but temp adjusted just fine. But I figured if I’m going to replace one, I might as well replace both while I’m in there since they are both moving parts with similar wear. I put the servos in and checked air before reassembling the glove box. Good news is the air does switch between, feet, face, and a mix of those and defrost. Bad news is there’s always air coming out of the defrost as well, no matter what position I switch it to. Less on some settings than others too? Not too worried for winter but with summer I’ll be fogging up my windshield with ac on it all the time. Is there something else I can double check or need to adjust before I reassemble the glove box.
Thanks in advance for any suggestions.

when you replaced it the piece that snaps on the servo with all the lines that looks like a mini maze(lack of proper terms) it has 3 legs that go in it the one way back is probably stuck out side the mini maze piece... it happened to me, I had to take it back apart and made sure they all lined up.

 

[Jenn1322]

when you replaced it the piece that snaps on the servo with all the lines that looks like a mini maze(lack of proper terms) it has 3 legs that go in it the one way back is probably stuck out side the mini maze piece... it happened to me, I had to take it back apart and made sure they all lined up.

Mini maze piece is a perfect description. I checked this morning and you were right. Since there’s so much space there to work and get your hands in there and see what’s going on at the same time, I can’t imagine how I didn’t get it the first time. LOL. I saw two for sure and I thought if the two were in place, the third had to be. But all in all, I’m really glad that’s the top servo. That bottom one I hope lasts 250,000 miles! Thanks for the help!

 

[Deb Mac]

any insight?

This is the most horrible job on a 4runner (maybe on every car). I have been putting off going anywhere near this until today.

My issue is the air con works perfect for all the car, but if I want heat it's only on the driver's side. Passenger side and the back vents blow cold air. I thought the issue was the bottom servo (airmix) and had purchased one many months ago and never put it on.

I had previously had a look and noticed the left screw was missing, either it worked its way out or someone had been at the system previously. To get to the really hard screw on the right of the servo I heated a chisel and melted a hole in the cabin filter slot. This worked and along with a scope I was able to remove the screw and got the servo out. I put the new servo in but unfortunately it didn't solve the problem, still no heat for the passengers.

Kinda well peeved at this stage, skinned knuckles and sweating like crazy... tip.. don't do this job on a 90 degree plus day. I figure it must be the top servo (for mode) and when I looked there is also a screw missing and the other two are loose. So someone has already had their hands at this and just didn't bother putting it back together properly. Not sure if I should put the money into buying the top servo just in case something else is the issue.

Any suggestions?

A big thanks to the op and his picture guide and also the tip about putting a hole in the filter slot it really made the job somewhat easier.

I have the same problem as yours - I only get heat from the driver's side. Mine is a plain old SR5, not dual climate, and in addition, I get low air flow on the passenger side vents (all 3) in addition to absolutely no heat. Heat and air flow are great on driver's side and rear, and a/c is perfect all through the truck - full force air flow and full cold. I'm still trying to find out how I could get air restriction on one side of the truck (feels like a door is closed - no heat coming through at all - feels like it's trying to push outside air through).

Did you ever find out what's going on? I have read in many posts that a partially blocked heater core could cause the cold vs heat one side vs the other, but in my mind, that doesn't explain the low air flow one side vs the other. My heater hoses are both nice and hot (195F if the heater isn't on, 195 in & 145 out if the heater is on full) so I can't see it being the heater core, unless i'm just missing something that the FSM doesn't explain).

Are there 2 separate blend doors controlled by the single servo? Is it possible that the one on the passenger side is stuck? And if so, is that anything that can be corrected without pulling the entire heater assembly?

Before I start dismantling the glove box and pulling and replacing servos, I would love to know if that will solve my problem. No point in mucking about trying to fix something that isn't broken and making a worse mess than I already have.

 

[stage3rides]

I am having a similar issue as listed in the thread but with something slightly different going on.

1. I have the loud buzzing upon startup and sometimes when cornering while driving coming from the passenger side

2. I can get air to blow from different vents but it is no longer cold - the ac was blowing very cold a couple months ago

3. I checked the air temp sensor under the ignition and it's clean and plugged in

4. I have removed the glove box and have access to the servos. My vent mode servo (top) works fine. My air mix servo (bottom) only moves from HI-78 degrees, below 78 degrees the servo no longer moves.

I am struggling to understand why the air mix servo functions normally through half it's range but stops working on the other half. If I replace this servo will it work properly again or is there another possible explanation that I'm missing? It looks like all the screws are in place and everything is plugged in properly as far as I can tell.



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[AuSeeker]

I am having a similar issue as listed in the thread but with something slightly different going on.

1. I have the loud buzzing upon startup and sometimes when cornering while driving coming from the passenger side

2. I can get air to blow from different vents but it is no longer cold - the ac was blowing very cold a couple months ago

3. I checked the air temp sensor under the ignition and it's clean and plugged in

4. I have removed the glove box and have access to the servos. My vent mode servo (top) works fine. My air mix servo (bottom) only moves from HI-78 degrees, below 78 degrees the servo no longer moves.

I am struggling to understand why the air mix servo functions normally through half it's range but stops working on the other half. If I replace this servo will it work properly again or is there another possible explanation that I'm missing? It looks like all the screws are in place and everything is plugged in properly as far as I can tell.



Sent from my Pixel 4 using Tapatalk

Inside there's a circular contact disk that rotates and is connected to the arm, there's contact "fingers" that makes the electrical connection to the contact disk, there's a "burned out" area on the circular contact disk so it will rotate and move the arm until it hits the "burned out" area and then the electrical flow/connection stops and the arm no longer moves.

 

[stage3rides]

Inside there's a circular contact disk that rotates and is connected to the arm, there's contact "fingers" that makes the electrical connection to the contact disk, there's a "burned out" area on the circular contact disk so it will rotate and move the arm until it hits the "burned out" area and then the electrical flow/connection stops and the arm no longer moves.

Thanks for the explanation, that makes sense to me. So i need to replace the servo to fix that burned out area, correct?

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[AuSeeker]

Thanks for the explanation, that makes sense to me. So i need to replace the servo to fix that burned out area, correct?

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Unfortunately yes, the disk has a copper plating on it and once the cooper burns/melts there no more copper to make contact in that area.

 

[theSKANT75]

Man, I wish I had found this thread last year. I bought my 08 limited with a v8 in March last year. It had a terrible buzzing sound that I’m sure you already know if you are here. It did help me negotiate a more favorable purchase price That being said I found the buzzing, unplugged the servo and manually set the dampers to defrost and dash just making sure to close the dash vents when I wanted defrost. It work for the last year but my wife drove the 4Runner and asked why she couldn’t get the darned thing to change the vents. I hadn’t found the part numbers for the servo as the denso numbers came up blank and finally broke down and went to the Toyota dealer to find a replacement part. I had a a lot of fun putting the new servo back in but could not get tot he last screw on the back side of the servo. I will head to home depot tomorrow and grab some of those hex head screws mentioned in the write up and see if I have better luck. It works fine as is but it really isn’t that big of a deal to get in there and do it right.

I would like to add that I cleaned the servo wheel with the slots in it really well and used some white lithium grease to make sure things were moving smoothly.


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[judogti]

Stupid question but Im working on replacing the top servo.

Whats the best way to unplug it? Should I unscrew it first? My hands dont fit to get the plug while its attached, but the wire harness doesnt seem to have enough extra play if I unscrew it to get it unplugged either?

Really trying not to break the plug before I get in there.

Thanks for this whole thread. So helpful.

 

[46runner]

Stupid question but Im working on replacing the top servo.

Whats the best way to unplug it? Should I unscrew it first? My hands dont fit to get the plug while its attached, but the wire harness doesnt seem to have enough extra play if I unscrew it to get it unplugged either?

Really trying not to break the plug before I get in there.

Thanks for this whole thread. So helpful.

I think either sequence would work. Can you get someone with smaller hands to unplug it?

 

[UncleStack]

Very helpful and useful thread! My questions is this, which I don't see asked or addressed:

When reinstalling the Mode module, is there a specific orientation the arms need to be in? Or will they auto-align so long as they are all in the correct slots on the mode wheel?

thanks!!

 

[locked up]

I have a 2003 Limited and don't get heat on the passenger side.

Am I correct in my understanding that IF this is servo related (not heater core related) this would be the "lower" servo on the passenger side next to the center console?
(green arrow in photo - not my photo)


... And that part number is 87106-35140 (replaced by 87106-35180)

... and that this is pretty easy to swap out?

 

[carypires]

useful for me

 

[Bahnstoermer]

The de-bug criteria I'm using is this:

If the chatter comes and goes based on selection of the vent location (low, high, defrost, etc) then it is the "mode" servo, 87106-35120...

Does that sound correct?

 

[Swimupstream]

The de-bug criteria I'm using is this:

If the chatter comes and goes based on selection of the vent location (low, high, defrost, etc) then it is the "mode" servo, 87106-35120...

Does that sound correct?

For me it just randomly chattered all the time. If you take the 15 minutes to pull the glove compartment and lower assembly off (like 5 or 6 simple bolts), you can stick your head up under there and watch them both. Change temperature and modes back and forth and you'll see which one is hiccupping.

Most people change it bc they have problems w temp or w vent changes. If it's just chattering annoyance and you are fine on both, you may be like me and be able to disassemble it, clean it up, add a little grease, and boom! All done!

(My own mode servo had also been reattached incorrectly so it was both issues)

Hope that helps!

 

[88Center]

Great writeup and pics. Very helpful. Thanks!

I have same 'click click click' noises coming from servos and need to fix. Driving me absolutely insane when I drive. Sometimes it's so loud, I have to blast the stereo to drown it out.

These servos aren't cheap. Current prices on Amazon.

Servo: 87106-35180 ($184)
Servo: 87106-35120 ($126)

 

[missionman]

Dang! I just replaced my TXV thermal expansion valve which fixed my AC issue but when reinstalling this damper servo sub-assembly for mode module (87106-35120) I thought I lined up the 2 little arms. I even cleaned and regreased everything with new lithium grease.
When testing my AC the modes dont do anything much. i can hear the module moving but nothing changes. Its stuck on forward vents.

You literally cant know if its in right until you test it fully installed. Does ANYONE have a diagram of the position of these little 3 prongs?
I moved the little prongs slightly while working on other stuff and Im not sure if they need to be in a certain position or if it doesnt matter.

 

[88Center]

Just finished replacing mine. One back screw caused a massive headache.

But to save others from possible headache, I did a clean writeup here.

Works like new now.

Replacing AC Servos / Actuators