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RX300 Air Mode Servo removal made easy

Old 09-22-17, 02:22 PM
  #76  
maxSteel
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Originally Posted by chenxingha View Post
I am stuck at loosening the top screw pointed by the RED arrow in the photo. There is less than a finger space between the screw top and the 2 aluminium tubes which are running in parallel with no gap between the 2 tubes.

I need advice about getting this screw off.

Thank you.
I was able to get around the tubes. But if you can't, try:
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Old 09-22-17, 03:17 PM
  #77  
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See the first photo in post #61 of this thread
https://www.clublexus.com/forums/rx-...ml#post7613271
It shows a regular screwdriver engaged with the screw. Or use one of the screwdrivers like maxsteel posted.
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Old 09-22-17, 05:24 PM
  #78  
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Thank you both MaxSteel and Lexmus. I hand-made a "tool"

that worked for me to get the top screw loose. The tubes are so close to the screw top that I cannot even get a screw bit in, much less to use a ratchet. The hand-made device allow me to get to the screw from an angle. It took me about 10 minutes to loose the screw. Now the air mix servo is off and here are the photos of it:







As it can be seen, the internals are clean, nothing appears to be out of the ordinary. The motor drive shaft has very little room to escape the notch. I cleaned the track and contact springs and lay a coat of di-electric grease in place. Put pieces together - this time did not break any thing - and will reinstall it back tomorrow morning.

While looking for replacement parts, I found on RockAuto that the vehicle has 4 different servos! The main bodies are look-like, the differences are with the control arms.
https://www.rockauto.com/en/catalog/lexus,2000,rx300,3.0l+v6,1363586,heat+&+air+conditioning,heater+blend+door+actuator,10721

RockAuto lists them as (1) Blend Door Actuator (2) Mode Door control (3) Temperature Door control (4) Recirculation Door control. Based on the physical shape of the listed devices, the Mode Door control (2) is the mode servo (that I replaced a little while ago) and the Temperature Door control (3) is the air mix servo (that I am working on now). But where are the other 2 servos? In my case, based on the clean internals of the 2 servos (mode servo and air mix servo) that I had opened so far I suspect that the rapid-firing clicking noise comes from one of the other 2 servos that I don't know where they are.

Last edited by chenxingha; 09-22-17 at 05:29 PM.
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Old 09-23-17, 08:17 AM
  #79  
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I have reinstalled the air mix servo, still using the home-made tool to tighten the top screw. It appears that a proper procedure might be to remove the mode servo first, which would then give work space to remove/reinstall this top screw on the air mix servo. I think this ultra low profile screw driver on Amarzon could then add to the effort:
Amazon Amazon

While I was under the glove box area to reinstall the air mix servo, I looked around and identified the 3rd servo, which is on the side-top of the blower motor box. Here is a looking-up photo with a RED arrow pointing to this 3rd servo:


This servo is controlled by the fresh air/internal circulation button, and I believe this is the (4) Recirculation Door control (servo) in RockAuto's list in my previous post.

After reinstall the air mix servo, I turned on the engine and the rapid firing clicking noise was not present. It has not been present when I was ready (on my drive way and have the glove box removed) and really need it to help identifying the culprit - a cat and mouse game I suppose.

A question still remains: where is the 4th servo, the one that RockAuto labelled for Blend Door Actuator, (1) in its list?
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Old 09-23-17, 08:30 AM
  #80  
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I recall reading in the thread that someone was asking for the mode positions. The mode sequence on my vehicle goes in these steps: face -> face + foot -> foot -> foot + defrost -> (back to) face. While I was in there, here are the photos for the corresponding positions:

face


face + foot


foot


foot + defrost
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Old 10-29-17, 02:17 PM
  #81  
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Well, my cleaning work of the motor in the air mix servo box appears to worked - it has been about 3 months and the continuing "rapid-firing clicking" noise has not happened! Also important is the low level rumbling noise (sound of something continuously running from the center column) is no longer present.

My experience shows that, when rapid-firing clicking noise appears, the right path of fixing it is to remove the mode servo and then the air-mix servo; open both servo boxes and wipe clean the resistance wheels as well as the contacting arms; then apply a think coat of die-electric grease onto the wheels; carefully bend the contacting arms just slightly to ensure good contacts; then reassemble everything back - hopefully, not breaking any locking tabs that forces the box closed tightly. Then put the 2 servo units back in the reversed order.

In my case, none of the 2 servo units had any observable physical damages. The replacement of the mode servo unit might not be necessary - it was replaced at a time I did not know there are other servos. I now know the positions of 3 servos and there is indication that there may be a 4th servo somewhere.
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Old 10-30-17, 02:12 PM
  #82  
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Thanks everyone who has posted in this section! After 2 years with no heat in my 2002 Lexus RX300, I found and ordered a mix servo from Amazon. My 18 year old daughter, who can do anything once she sees it on you tube, took apart the "guts" after I removed the glove box. She replaced by dead mix servo with the new one and voila, we have heat!!!! Just in time for our cold spell. Thanks again folks!

(she also removed a full size sheet of paper from the blower motor which solved our noise problem.)
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Old 11-07-17, 12:39 AM
  #83  
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Hey all, I just got a 2001 RX300, I believe my mode servo is dead. I'm going to take it apart and see if I can fix it or replace it. Do you guys think this tool would work good for that hard to reach screw?

https://m.harborfreight.com/hand-tools/screwdrivers/33-piece-precision-screwdriver-set-93916.html

or this

https://m.harborfreight.com/8-piece-right-angle-screwdriver-92630.html
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Old 11-08-17, 04:38 PM
  #84  
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Probably the right angle would be more useful than that set. Or you could use one of the bits in that set in a vise grip
But this thread has other tool suggestions I'm sure.
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Old 11-09-17, 09:03 AM
  #85  
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Default Ummm

So um. Looks like the morons that fixed the mode servo before me only put in 1 screw, so good news is I don't have to fight that pesky 3rd screw! Yay! Bad news is, it's stuck in defrost/floor and doesn't want to wiggle out of the track. Any advice?

Edit: oops. Nevermind. I was looking in the wrong place. I do in fact get to fight the third scew. And I'm gonna lose. 😓

Well finally got it with some help. Tried to fix the worm screw a few times. It would work for a min then stop. Ended up just buying a new one. Got a lifetime warranty though! Also, noticed there is another servo up above this one, that doesn't open up all the way and lets some air leak out the vents when i change it to floor. It's good enough for now though. I got what I wanted done.

Last edited by Andro; 11-09-17 at 12:15 PM.
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Old 10-06-18, 11:29 AM
  #86  
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I wanted to say thanks to dimitrov for his recommendation. I just completed exactly what he recommended and it worked exactly like he said. It wasn't without a few curse words at the Recirculation Servo though. To remove this servo I had to remove a wiring harness bracket to reach the last screw. The new motor is strong enough to move the air mode servo into the face mode. Before the servo would move it out of this position but not back.

Also to address the pesky third screw, I used a 1/4 in drive with a 1/4 in socket with a Phillips head bit. This allowed me to remove and put the screw back in. I also removed the floor duct which gives you more room to work. This post saved me a couple of hundred dollars. Thanks for all that have contributed.




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