to check them just run through all the settings (with a passenger in the car would be easiest ) and see which one you have problems with or which one causes the "noises" again

 

when i cycle through MODE, it seems like the noises stop and then start up for a bit.. i guess that seems to be the culprit...

 

I noticed someone else posted a question about just replacing motors; has anyone done this and tried it?

I suspect only the motor needs to be replaced (assuming the teeth on the gears are good) just like the problematic Door Lock actuator problems where only the motor needs to be replaced.

If someone has an old servo and can get me all of the numbers on the motor (please take pictures too) I will be glad to try this as a fix. Please let me know if the motors are the same for the Mode and Passenger Temp.

This would be a cheap fix as motors are probably less than $5.

 

After opening these things up and seeing they are just a couple gears and a 50 cent electric motor I couldn’t spend $150 on new ones. If there was something wrong with the motor I believe it wouldn't make the noise at all. After a little playing around I found the defect in the design and IT IS VERY EASY TO FIX! If you were able to get the servos out then you can definitely do this.

This gap (circle A) allows the worm gear to slide down the axle where the axle can no longer grip it (circle B). The noise comes from the worm gear not being in proper contact and it doesn’t get enough torque to properly function. The intake servo on the blower, which no one seems to have problems with, DOES NOT HAVE THIS GAP. The worm gear is seated snug with no room to slide.

The fix: My answer was to put a drop of some good adhesive in the worm gear and spread a thin layer on the shaft. I used goop ultra and let dry overnight. So far so good.

I'm confident of the identification of the problem but the fix is still new so I’ll see how it holds up. Suggestions and new fix ideas are welcome. Better adhesive? Method to fill the gap? Longer worm gear? Regardless I'm pretty sure I just saved myself $300 and I would feel terribly guilty not sharing with you guys.

 

Let us know how that works out, certainly makes some sense. What's weird is the pic above yours does not look like it would be able to move that much. Might want to try to shim it down with something on the end to trap it if the glue does not hold.

 

both servos working PERFECT after about 2 weeks. Please guys don't wastes your money, these things are VERY EASY TO FIX.

 

Agreed. After looking at the one I replaced I was able to slide the end bushing 3/32" out of it's "trap." If the problem is worm gear length wear shimming that area should work. What concerns me is how folks are resolving this issue by replacing motors and not worm gears.

 

Were these "mode" or "temp" servos that you did this fix on?

 

Hey guys...as I posted on another thread, you can just slide the brass bushing slightly up the shaft to compensate for the gap. I had to slide mine up about 1/8". So far this seemed to work and this fix makes alot of sense to me. The motors and servo seemed fine.

BTW, this problem was on the Mode servo. I did take out and inspect the air mix servo, but this one was fine - no gap.

Be sure and mark the position of the arm on the servo with a permanent marker. I didn't do this and ended up spending more time trying to calibrate this.

 

I love how this solution keeps getting more and more simple! Nice work.

 

Many thanks to fingershop for his excellent write up of how to fix the servo motors. This is a must read right here:

https://www.clublexus.com/forums/gs-...rvomotors.html

Many people said to “clean the contacts” but he explained HOW and WHY, which enabled me to know what I was doing and get it done right. Big kudos.

Thank you to sakataj for posting pictures on removing the passenger and mode servos.

Thank you to dRo15 for posting pictures on removing the driver servo.

I successfully removed, cleaned, and reinstalled three of my servo motors (driver, passenger, and mode) using the information these guys gave, on my ’99 GS300. And now they are working great, and the noises in my dash are gone! I wish I would have done this two years ago!

So here is my contribution back to all those of you who are still READING and trying to figure out how to go about this, as I also read a lot of misleading information about these servo motors. I will attempt to clear much of this up…

There are 4 servo motors: driver’s side temperature control, passenger’s side temperature control, mode control, and fresh air/recirculation control.

DRIVER SERVO
The driver servo is located underneath the driver’s side of the dash. The other three servos are all grouped together under the passenger side of the dash.

The driver servo is by far the easiest to access, of the four servos. It is located a foot above the gas pedal, fastened to the wall just left of the radio, at the height of where the carpet meets the trim. After simply removing the cover under the driver side dash, you can pull the carpet back and see it and touch it, including its gear arm. I was quickly able to determine that my driver servo was the culprit making the “gerbil” and “clicking” noises in my dash by simply pulling this carpet down a bit and being able to FEEL the gear arm moving frantically back and forth continuously. I could also distinctly HEAR the clicking sound when I stuck my head down there above the gas pedal and put my ear up next to the driver servo.

To get to the driver servo for removal, all you have to do is take off the cover under the driver side dash. It has two screws and two clips. The two screws and one clip you can see. The hidden clip is right in the middle at the front of the piece. You just have to give a little yank/wiggle to pop it forward. Then slide the cover back to slip it off its latch. Super easy. There is no need to take out your driver’s seat for room, or your passengers seat for that matter. And it’s not necessary to lie on your back with your feet all the way up your driver’s seat. I just put a folded towel for padding on the door sill and laid on my back across that. I’m 6’2” 240. If I can get in there, most people should be able to also.

The most difficult screw to take out and put back in was the top screw of the three, for the driver servo. It’s not too hard to reach…you just can’t see it, and you are working in a pretty tight space. Again, you better make sure you have a stubby screwdriver when doing this job. The top screw was an exercise of seeing blind by feel.

MODE & PASSENGER SERVOS
The mode servo is accessible in front of the passenger servo. The mode servo is easy to identify because it has a wide fan-shaped white gear arm. The passenger and driver servos both have a simple straight white gear arm. The passenger servo is located deeper behind the two aluminum heater pipes. And yes these pipes are hot after the vehicle runs, so beware to let them cool down. I did not find it difficult to get the screws out and back in for the passenger servo, even with the pipes there. It was cumbersome no doubt, but really only took a few minutes. A STUBBY SCREWDRIVER IS A MUST! The only other tool needed for removal during this job is a 10mm socket wrench, and some flashlights. To open and clean the servos I used a mini flat-head screwdriver, cotton *****, Q-tips, and isopropyl alcohol.

In removing the passenger side lower dash, I did not need to remove the blower fan. And instead of prying off half of the white plastic shroud/air-tube vent, I took the whole piece out. Its third screw is behind the plastic console trim, fyi.

FRESH AIR/RECIRC SERVO
I did not remove the fresh air/recirc servo, as it has been said by many that this one is not known to malfunction. Whether this is true or not, I don’t know, but it makes sense that it would not malfunction like the others. Because it only has two positions, open or closed, it doesn’t have to search its potentiometer for position. It moves all the way one way or the other, whereas the other 3 servos all move to various in-between positions wherein a dirty potentiometer could result in a loss of known position.

The fresh air/recirc servo can be seen at the same time as when removing the glove box to get to the passenger and mode servos. It is behind the CD changer and to the left of the cabin filter. After pulling out the glove box, I also took the opportunity to remove the cabin filter, shake it out, and slide it back in.

“MYTH BUSTERS”
The following are other people’s opinions on how to fix the servo motors that didn’t apply in my case:

Username “mindfull” said the worm gear may have too much room, or a gap, at its end which allows the worm gear to slide off its shaft and disengage from the motor. This was not the case for me. My worm gears all had no gaps at their ends. Everything fit snug and tight.

Someone said to insert a washer above the potentiometer gear to make it fit more snug against the contact arms. I looked into doing this with my servos. It did not appear to be necessary, as when the cover is snapped back on, it presses the potentiometer down an extra 3/16th of an inch. This was more than enough pressure to force all the contact arms down.

It has been said to snap the arm off of the passenger servo in order to access the potentiometer for cleaning, and then super glue it back together. I feel like I was able to clean the dark contaminated grease off of the contact arms and potentiometer using Q-tips and just reaching underneath the potentiometer without having to break off the arm to get to it. I can’t say whether I did a perfect job because I can’t see the result, but I did see that I removed quite a bit of dark contaminated grease with my Q-tips. I then spun the potentiometer around several times using a fresh Q-tip to spread the good grease around the whole potentiometer’s surface. FYI, you must take out the motor in order to spin the gears. I would suggest going the route of cleaning under the potentiometer first and seeing if that fixes the servo, before resorting to breaking the arm off and regluing it. Though I think a break and glue could work too, I guess.

It was said that you can disconnect the arm from the passenger servo without breaking it. I inspected this arm closely and could not see how this is possible.

Some people have speculated that the plastic gears wear out, causing the servo to fail. I did not see any wear on the plastic gears whatsoever.

Some people have speculated that the gears aren’t in good enough contact to turn each other, or get off track or out of alignment. I didn’t see this whatsoever. It may be possible for the gears to come loose when you open the servo, but once you clip it back together, everything is pretty tight in there.

Some people have speculated that the MOTORS are failing. This was not the case for me. The motors all looked to be just fine. After cleaning the potentiometer, the servo went from malfunctioning to working like new.

Some people have said to clean the contacts where the electrical plug plugs into. No, these look perfectly new. The only place needing cleaning that I could see was where the contact arms rub against the potentiometer.

CLEANING THE SERVOS
The way that I cleaned the potentiometer was as fingershop outlined. I used a cotton ball with isopropyl alcohol to clean the dirty grease off the contact arms as well as the section of the potentiometer that was scraped and dirty. The dirty section is only about 90 out of 360 degrees of the potentiometer. Next, I cleaned my index finger and used it to spread the good grease on the potentiometer evenly around the whole surface. For good measure, for the rest of the servo’s gears, I also smeared some of the existing grease around these other parts within the servo where I figured it should be, like at the tops and bottoms of the gear shafts, for easy spinning, and then clipped the servo closed.

FYI, the driver servo and mode servo both have the potentiometer facing up and are accessible for cleaning, when you open them. Only the passenger servo potentiometer is facing down and therefore hard to clean.

TESTING THE SERVOS
With the servos installed, and before putting the dash back together, it is easy to test that they are working. When you turn the key to the ON position, the white servo arms will move a little bit to initialize. When you adjust the temperature up and down on the driver’s side, the driver servo arm will move up and down. The higher you move the temperature the higher the servo arm will move up, the lower the temperature, the more it will move down. When you adjust the passenger temperature up and down, the passenger servo arm will move up and down. When you press the Mode button, the mode servo will move to different positions as you cycle through feet, face, windshield, etc. When you push the fresh air/recirc button, the fresh air/recirc servo arm will go up or down and you will see the big vent above the blower open or close.

You can tell that the servo is working correctly if it moves responsively to your commands and stops. If it is malfunctioning, it will move erratically continuously because it is lost.

Now that you are no longer lost, go fix your servos!

 

So if my air is not cold enough and it has different temps on each side

is this the reason?

 

I have a customer with a 2003 Sport Design and the cold air only blows to the windshield. Looks like I'll be changing out the mode door actuator for them.

 

Just did the worm gear mode servo fix last night. Cost me $0.00 to repair. I just pulled off the worm gear and put a dab of adhesive on the shaft of the motor.

Amazing and simple solution to a pesky problem.

Big thanks to all who took the time to contribute to this thread.

 

Hi, your info seems great, but I will not be doing my own repair, last year I had the blend air motor replaced, they took some pics to show me what a job it was - the car had been making annoying clicking noises..........well the noise did not go away and then the car started to chirp like a bird - now it has started to groan.........and is happening more and more often. This only happens on the mode that feeds the air to the main vents in front of you - if I put it on the main/floor vent mode it goes away and same if just on floor - so after reading these msg/s think it is the mode servo - and the noise seems to come only from the left vent of the passenger side.

So my question is since I won't be able to make these repairs how much should this cost, can my mechanic clean them or should he just replace it - I have a 2000 RX 300.

I also need to have the master cyclinder replaced, have noticed for a while that when I am stopped the brakes then release and I must press down more on the brake pedal. What should I expect this to cost to?

Thanks, for any help and and suggestions you can provide.