BBLexus

I have an 02 RX300 and recently I have been hearing a strange clicking noise coming from within the dash, possibly behind the radio unit. The radio and CD work fine but this sound has been starting to concern me now that I notice it more often. It is sporadic, it doesn't alway occur, maybe every few days. It is a faint sound, you wouldn't notice it unless you had the air conditioning/fan off. I usually hear it when I am siting still in traffic or when I am driving on smooth pavement. That's when I hear the clicking noise coming from the dash. I have the 6 CD multipack in the glovebox and that is working fine. The sound almost reminds me of the sound of the CD player switching CDs, which it isn't - I just have the radio on. I haven't had time to narrow the down the problem since it is sporadic, but I do know it only works with the ingnition on and the radio on, but now while a CD is playing which leads me to believe it is CD player. Anyone else have this problem - if so, what did you do to resolve it?

carguy07

Yep, air mix servo. Just search the word "servo" and you will find a ton of info.

BBLexus

Thank you carguy07 - your suggestion took me to some postings that are probably the exact issue. thanks for the direction.

BBLexus

I finally got around to taking out the 'forward' air mix servo (if that is correct name for it) by following the instructions below. My recommendations are that you remove the duct piece that is in the way of getting to the servo screws. If you remove the duct, you can use a rachet driver with a philips head bit to access the screw that is on the backside closest to the firewall. I would also take a picture with a phone or digital camera so you can reset the 'arm' in the previous position thus making reinstallation easy. sorry that I didn't take pictures. I too broke two of the clips but it is a simple task of cleaning the servo inside as described however just getting to it and doing the work with your screw driver is what will take the most time. Thank you for the instructions, they made it easy. I tested the servo after reinstall and no strange noises so hopefully this will last without the need for futher work.

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https://www.clublexus.com/forums/sho...ighlight=servo

Lil4X
Ol' Inkslinger


Join Date: Aug 2001
Location: Houston
Posts: 6,859

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A while back someone reported a similar problem and Tracilex over on the LOC forum had an answer. Apologies, I am not able to make the link work, so here is his fix.

Quote:
I think I've got this one licked...

The noise is coming from the servo motor that moves the door for the "mode" button. This servo moves diverters to change from vent to floor, etc.
- I popped the bottom panel off under the glove box.
- I then removed the glove box assembly. 2 screws up high, 2 bolts down low.
- With the key on engine off you can press the mode button and watch the servo move. Turn the key completely off.
- Remove 3 screws and plug to take the assembly out.
- Do not attempt to rotate the arm on the end of the servo. It engages w/ a worm gear. Turn it and you will break gears.
- The servo is a snap together unit. Carefully take it apart w/ the arm side down.(so gears don't fall out)
- inside you will see multiple wiper fingers that make contact w/ a gear. Carefully clean these w/ alcohol and a cotton swab.
- Redistribute the contact grease on the wiper pad w/ a clean finger (any oil or lotions on skin will mix w/ the grease and make the copper contacts corrode.
- Carefully snap unit back together.
- Clean contacts on the outer part of servo also w/ alcohol.

The other option is to have Lexus diagnose this for you and hit you for $160 for the part plus ~ an hour or 2 labor.

So far the noise is gone and the HVAC system works properly. I will post any updates if the problem comes back. I think the problem was caused by crusty contacts in the servo that were creating a poor signal back to the computer that controls it. Now that it has a clean signal, all is well..... I hope!!!

Thanks to Tracilex and the Lexus Owners' Club!
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Nickv

Wow! Was my return to Club Lexus timely. I just started hearing this click in my dash about two weeks ago. Actually, I didn't hear it, but my wife did. I hear almost nothing...age related hearing loss.... ugh. As usual, I will wait until the problem gets worse before tackling. But at least I know where to go for the answer. I WILL return and report back how my diy repair works, or not. But only after I "fix" it. Thank you guys so much.
NIck

huntergts

NickV, I'm having similiar problems with my air mixing servo. Please post pictures of your work.

Are you guys adding new grease or re-using the existing? If adding new what kind are you using?

Nickv

Huntergts: I wish I could help you, but the Lexus dealer took care of my problem via the extended warranty. They said they replaced an expensive small computer... As it didn't cost me anything, I didn't really pay any attention to what they actually did. I AM getting one of the cheap OBD II readers from Harbor Freight in anticipation of future repairs. I love my Lexy and intend to keep it for some time, even if it is 8 years old now. Hell, I'm 68 and still ticking...though not as fast as before. As for grease? Beats me. Look at previous posts by the "experts", they know what they are doing.

BBLexus

I didn't add grease. I cleaned the surface area with a cotton swap and alcohol for the metal flanges or fingers and removed the tarnish. For the surface of the 'wheel' I used a clean cotton swap to remove any residue - but didn't use alcohol. I then captured a small amount of the lubricate/grease that was clean and still on the wheel and applied a coating to the area the flanges or fingers contact on the wheel.