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Discussion Starter · #1 · (Edited)
Yesterday I started hearing a ticking noise accompanied with a struggling electric motor sound. The sound came and went when I cycled the temperature from cold to hot and back to cold. I then proceeded to take the glove box off and I could feel the air mix servo pulsing/ticking when the temperature is set low.

After removing the glove box and part of the HVAC ducting that directs air into the passenger front footwell, I can see two screws that holds the servo motor down, but I'm thinking that there is another screw behind the heater core pipes. Has anyone replaced their air mix servo and can share some DIY tips? Will I need to pull the heater core out ... or is there a workaround?

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Update: See post #2 for air mix servo part number (post #4 for other servo part numbers) and post #10 for removal and install steps.
 

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Discussion Starter · #2 · (Edited)
Update: Oddly, the servo motor stopped making noises this morning. I'll keep an eye on this ... maybe even remove it and clean out the servo arm one of these weekends. I think I can get this off with an offset Phillips screwdriver.

*EDIT* BTW, I called up a Lexus dealership and was given the following part number for the air mix servo:

87106-30341
 

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Anyone else replaced their servos? I have a buzzing noise coming from them, took it to the shop and they said both servos need to be replaced at $1100.
Is this a tough procedure? Where can I go to buy the part?
 

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Discussion Starter · #4 · (Edited)
Anyone else replaced their servos? I have a buzzing noise coming from them, took it to the shop and they said both servos need to be replaced at $1100.
Is this a tough procedure? Where can I go to buy the part?
Unfortunately, since the noise stopped I got lazy and never took out the air mix servo.

I did figure out the part numbers for the other two servos (there are 3 overall when you include the one I mentioned in the first post). Here they are:

87106-30371 = outlet servo (used when you cycle through the fan modes)
87106-30410 = inlet servo (used when you hit the button to recirculate or use outside air)

You can buy these online from l-tunedparts.com. Here's a shipping promo that they are running:

http://my.is/forums/f131/l-tunedparts-0-99-cent-shipping-promo-oem-parts-388592/



Before you spend the money, make sure it really is all servos that need replacement. Try the following to troubleshoot:

1. cycle temperature from hot to cold or viceversa = air mix servo
2. cycle through the fan modes = outlet servo
3. cycle between recirulate and outside air modes = inlet servo
4. cycle fan speed from low to high or viceversa = blower motor

So, if the noise goes away when going through any of the above ... that's the part to replace/repair.

Replacement of the servos does not look too bad, just need to get a screwdriver in there to get to the scews that hold them down. One of these days, I'll need to take out that air mix servo.

Hope this helps.
 

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I've changed one of the servos that controls the door for hot and cold air.

I bought a servo motor from ebay for $35 shipped from a guy who sells lexus parts off of salvaged IS300's and paid $50 to have a local mechanic install it.

You should search for the repair manual and it shows the location and steps to access it.

Toyota quoted me nearly $600 for the same repair.




Unfortunately, since the noise stopped I got lazy and never took out the air mix servo.

I did figure out the part numbers for the other two servos (there are 3 overall when you include the one I mentioned in the first post). Here they are:

87106-30371 = outlet servo (used when you cycle through the fan modes)
87106-30410 = inlet servo (used when you hit the button to recirculate or use outside air)

You can buy these online from l-tunedparts.com. Here's a shipping promo that they are running:

http://my.is/forums/f131/l-tunedparts-0-99-cent-shipping-promo-oem-parts-388592/



Before you spend the money, make sure it really is all servos that need replacement. Try the following to troubleshoot:

1. cycle temperature from hot to cold or viceversa = air mix servo
2. cycle through the fan modes = outlet servo
3. cycle between recirulate and outside air modes = inlet servo
4. cycle fan speed from low to high or viceversa = blower motor

So, if the noise goes away when going through any of the above ... that's the part to replace/repair.

Replacement of the servos does not look too bad, just need to get a screwdriver in there to get to the scews that hold them down. One of these days, I'll need to take out that air mix servo.

Hope this helps.
 

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Also the ticking sound is normal. If you do a search you'll see its common and not a problem.

Yesterday I started hearing a ticking noise accompanied with a struggling electric motor sound. The sound came and went when I cycled the temperature from cold to hot and back to cold. I then proceeded to take the glove box off and I could feel the air mix servo pulsing/ticking when the temperature is set low.

After removing the glove box and part of the HVAC ducting that directs air into the passenger front footwell, I can see two screws that holds the servo motor down, but I'm thinking that there is another screw behind the heater core pipes. Has anyone replaced their air mix servo and can share some DIY tips? Will I need to pull the heater core out ... or is there a workaround?
 

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Discussion Starter · #7 · (Edited)
Appreciate the info! I did end up looking at the service manual and it mentions removing the heater core to get to the air mix servo. This is the same servo that you replaced ... would you happen to recall if this is what you did to replace that servo?

I do agree that the servo does tick as part of its normal operation, but what I heard was different than what I had been hearing over the years. The air mix servo would tick once every couple of seconds and in between the ticks it would make a whirring noise (not the normal sounds, but more like a stuck/struggling electric motor sound) for what seemed like 1-2 minutes. Then it would stop, but then do this again several minutes later. It did this for three straight days. Then one day it stopped doing this and I have yet to have this repeat. Sorry, I'm probably not explaining this too well.
 

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No the mechanic didn't have to remove the heater core, there was a duct to that had to be moved and you can put in the servo at that point. The servo that I changed was the one that was further in.
 

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Discussion Starter · #9 ·
No the mechanic didn't have to remove the heater core, there was a duct to that had to be moved and you can put in the servo at that point. The servo that I changed was the one that was further in.

Cool ... this is the same servo that I'm referring to. Thanks! +rep
 

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Discussion Starter · #10 · (Edited)
Update: I decided to take the air mix servo out today as the air mix servo started making the noises that described above again last night. It is definitely a PITA from the lack of working space. Not sure if this is the problem, but I noticed that the outlet servo has a ton of grease (looks like lithium grease) on it, while the air mix servo hardly had any. I ended up taking some of the excess grease from the outlet servo and putting it on the air mix servo's arm and the corresponding arm to the air mix servo on the A/C unit (that's what it is called in the service manual).

Anyway, here are the steps I took to remove it ... sorry no pictures:

1. Take out glove box (Hint: Slide out the two pins at the hinge area).

2. You will see a HVAC duct ... there is an upper and lower piece. Take out the lower piece. It is attached to the upper duct with with a upper and lower tab that is molded into the plastic ... and it is also screwed into the blower motor. (Hint: You'll need to stick your head into the footwell area to see the lower tab between the upper and lower duct and the screw to the blower motor). Once the lower duct is disengaged, pull the connector on the lower duct ... and pull it down and out of the way.

3. You will now see the air mix servo (Hint: It is the one behind the metal pipes). It is held down with three screws. Two are in plain sight, the third one can be seen when you stick you head into the footwell and look rearward of the two pipes. You can remove these screws with a #0 Phillips precision screwdriver (Hint: You may need to loosen a bracket that holds the pipes down to allow you to push the pipes a forward little to get more space for the screwdriver).

4. Pull out air mix servo and disconnect the connector to the servo.



To reinstall:

1. Clean and grease the arm of the air mix servo and the corresponding arm on the A/C unit.

2. Reconnect servo to wire harness.

3. Insert the air mix servo back into position ... make sure to re-engage the servo arm with the corresponding arm plastic arm on the A/C unit.

4. Reverse the steps from the removal steps 1-3.



Hope this helps those that will need to replace (or clean and re-grease) their air mix servo in the future.
 

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Jet-
I did exactly what you said with the air mix servo, and now that I have it greased up, and reinstalled. I dont have any hot air. All that blows is cool air.
The AC blows cold, but when I put the heat on all I get is cool air.
Also all the functions work properly as far as where the air blows.

Would replacing the air mix servo get my heat back?

Please help
Thanks
 

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Jet-
I did exactly what you said with the air mix servo, and now that I have it greased up, and reinstalled. I dont have any hot air. All that blows is cool air.
The AC blows cold, but when I put the heat on all I get is cool air.
Also all the functions work properly as far as where the air blows.

Would replacing the air mix servo get my heat back?

Please help
Thanks
 

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great write up
 

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Discussion Starter · #14 · (Edited)
Jet-
I did exactly what you said with the air mix servo, and now that I have it greased up, and reinstalled. I dont have any hot air. All that blows is cool air.
The AC blows cold, but when I put the heat on all I get is cool air.
Also all the functions work properly as far as where the air blows.

Would replacing the air mix servo get my heat back?

Please help
Thanks
Was the heat working prior to the removal of the servo motor? If so, and the air mix servo is operational, then the servo motor arm may not be hooked up to the pin on the arm that opens and closes the blend door. Also, check to make sure that you re-connected any connectors that you may have disconnected.

My basic understanding is that the air mix servo motor opens and closes a door (blend door) that allows air to flow through the heater core. The heater core is what heats up the air. However, if the air mix servo is not operating, then you can also run into a problem where there is no heat.

Hope this helps.
 

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good write up....to give u visual guys some ideas this is what the process is like on my gs430

DIY on changing servo motors - Club Lexus Forums

IMHO it is NOT worth the time to take them out and re-grease them as that's just a band-aid, also if your in there fixing them, WHILE you there, go ahead and replace both the temp and mode servo's trust me its not worth doing one, putting it back together, then next one going out a week l8r or something and have to do it all again
 

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good write up....to give u visual guys some ideas this is what the process is like on my gs430

DIY on changing servo motors - Club Lexus Forums

IMHO it is NOT worth the time to take them out and re-grease them as that's just a band-aid, also if your in there fixing them, WHILE you there, go ahead and replace both the temp and mode servo's trust me its not worth doing one, putting it back together, then next one going out a week l8r or something and have to do it all again

The IS' servo replacement isn't as complicated as the link you posted for the GS. There is a post out there showing the step by step process if anyone cares to search for it.

I changed out one servo a year ago and fortunately none of the others have gone bad.

The reason the servo in my car went bad was related to the coolant in my radiator. So checking fluids regularly is a part of the preventative maintenance you should look out for.
 

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The IS' servo replacement isn't as complicated as the link you posted for the GS. There is a post out there showing the step by step process if anyone cares to search for it.

I changed out one servo a year ago and fortunately none of the others have gone bad.

The reason the servo in my car went bad was related to the coolant in my radiator. So checking fluids regularly is a part of the preventative maintenance you should look out for.
sorry, never implied it was as complicated as our gs's are. was just showing some people the process we go through as you'lls is probably similar.

oh FYI, i manage a heating and air supply house so this is my trade and servo's DONT go out due to coolant. EVER......they are a normal wear and tear item and will go out after use but they dont run off the coolant nor would low coolant matter to the servo :)
 

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Discussion Starter · #18 · (Edited)
good write up....to give u visual guys some ideas this is what the process is like on my gs430

DIY on changing servo motors - Club Lexus Forums

IMHO it is NOT worth the time to take them out and re-grease them as that's just a band-aid, also if your in there fixing them, WHILE you there, go ahead and replace both the temp and mode servo's trust me its not worth doing one, putting it back together, then next one going out a week l8r or something and have to do it all again
Thanks! I do agree with what you posted about just replacing the servo. In fact, that was what I was planning to do at the beginning. It's been awhile since I re-greased the servo arm and have not heard anything beyond the normal adjustment noises from the servo. But if it ever makes the minute long struggling motor sounds like before, I will replace it.

Hopefully, the thread helps anyone that runs into something similar.

The IS' servo replacement isn't as complicated as the link you posted for the GS. There is a post out there showing the step by step process if anyone cares to search for it.

I changed out one servo a year ago and fortunately none of the others have gone bad.

The reason the servo in my car went bad was related to the coolant in my radiator. So checking fluids regularly is a part of the preventative maintenance you should look out for.
My memory is fuzzy on the other two servos .... but I do recall that it looked easier than the air mix servo. I think the outlet (fan mode) servo was accessed by just taking off the HVAC ducting that I refer to in the steps. For the inlet servo, I believe there is a bracket with connectors in the way that would need to be moved. Don't quote me on this though as I last looked at this months ago.
 

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Can you give any more detail on what bracket you removed to allow you to move the pipes? Is it the one on the pipes closer to the top of the dash? I can't seem to get even an offset screwdriver up there.

I was hoping I could at least manually manipulate the hot/cold air mix door but the servo seems completely seized up.
 
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