Rh Airmix Damper Servo Assembly ('04 Rx330)

[RX330_2004]

When ignition key is on there is a noise coming from the area near the passenger footwell. The noise is like a mechanical cycling/clicking. I removed the small panel on the right side of the center console (2 each 1/4 turn fasteners) and the panel above the passenger footwell (disengage 3 each clips and disconnect power cable to LED illuminating the footwell).

Upon peering into the right side of the center console (laying in the front passenger footwell area) I could see the white plastic mechanism trying to turn with the airmix damper servo subassy driving it. I disconnected the power to the servo and the operation stopped.

How do I determine what is causing the servo to continue running?

(1) Is it getting a bad signal, i.e. position sensor not achieving the commanded position so it keeps running?

(2) Is the motor jammed/inoperable?

(3) Is the mechanism on the heater box jammed/inoperable?

(4) Other?

Are there error codes that would lead me to the answer? If so what are the codes and how do I access them? I have an OBDII scan tool but in searching this board it appears there's a way to get the climate control display to provide codes. If that's right where can I find the instructions on how to do that and the codes?

The servo is held to the heater box with 3 screws. The lower 2 are accessible, the 3rd is hidden behind an airduct that seems to be held in place with one bolt. Can I remove this bolt and hence that airduct to access the 3rd/hidden servo screw?

Thanks,

William

2004 RX330

20,500 miles (yes 20.5K miles)

Build Date 10/03

[wwest]

When ignition key is on there is a noise coming from the area near the passenger footwell. The noise is like a mechanical cycling/clicking. I removed the small panel on the right side of the center console (2 each 1/4 turn fasteners) and the panel above the passenger footwell (disengage 3 each clips and disconnect power cable to LED illuminating the footwell).

Upon peering into the right side of the center console (laying in the front passenger footwell area) I could see the white plastic mechanism trying to turn with the airmix damper servo subassy driving it. I disconnected the power to the servo and the operation stopped.

How do I determine what is causing the servo to continue running?

(1) Is it getting a bad signal, i.e. position sensor not achieving the commanded position so it keeps running?

(2) Is the motor jammed/inoperable?

(3) Is the mechanism on the heater box jammed/inoperable?

(4) Other?

Are there error codes that would lead me to the answer? If so what are the codes and how do I access them? I have an OBDII scan tool but in searching this board it appears there's a way to get the climate control display to provide codes. If that's right where can I find the instructions on how to do that and the codes?

The servo is held to the heater box with 3 screws. The lower 2 are accessible, the 3rd is hidden behind an airduct that seems to be held in place with one bolt. Can I remove this bolt and hence that airduct to access the 3rd/hidden servo screw?

Thanks,

William

2004 RX330

20,500 miles (yes 20.5K miles)

Build Date 10/03

Easy question to answer...

The servomotor has an integral position feedback, a "potentiometer", variable resistor. With the connector disconnected from the servomotor/FB use a voltmeter to check if the servomotor drive voltage is still varying back and forth. If it is the problem is elsewhere, other wise the servomotor's internal position FB is questionable.

If it is only the passenger side reheat/remix servomotor doing the "clicking" then other than the servomotor assembly itself the passenger side solar radiation sensor is "suspect", next on the list.

[RX330_2004]

When ignition key is on there is a noise coming from the area near the passenger footwell. The noise is like a mechanical cycling/clicking. I removed the small panel on the right side of the center console (2 each 1/4 turn fasteners) and the panel above the passenger footwell (disengage 3 each clips and disconnect power cable to LED illuminating the footwell).

Upon peering into the right side of the center console (laying in the front passenger footwell area) I could see the white plastic mechanism trying to turn with the airmix damper servo subassy driving it. I disconnected the power to the servo and the operation stopped.

How do I determine what is causing the servo to continue running?

(1) Is it getting a bad signal, i.e. position sensor not achieving the commanded position so it keeps running?

(2) Is the motor jammed/inoperable?

(3) Is the mechanism on the heater box jammed/inoperable?

(4) Other?

Are there error codes that would lead me to the answer? If so what are the codes and how do I access them? I have an OBDII scan tool but in searching this board it appears there's a way to get the climate control display to provide codes. If that's right where can I find the instructions on how to do that and the codes?

The servo is held to the heater box with 3 screws. The lower 2 are accessible, the 3rd is hidden behind an airduct that seems to be held in place with one bolt. Can I remove this bolt and hence that airduct to access the 3rd/hidden servo screw?

Thanks,

William

2004 RX330

20,500 miles (yes 20.5K miles)

Build Date 10/03

Easy question to answer...

The servomotor has an integral position feedback, a "potentiometer", variable resistor. With the connector disconnected from the servomotor/FB use a voltmeter to check if the servomotor drive voltage is still varying back and forth. If it is the problem is elsewhere, other wise the servomotor's internal position FB is questionable.

If it is only the passenger side reheat/remix servomotor doing the "clicking" then other than the servomotor assembly itself the passenger side solar radiation sensor is "suspect", next on the list.

Thanks for the prompt and informative response!

Another piece of info I forgot to add is that the noise will stop after being on some apparently random amount of time (i.e. I haven't resolved what that amount of time may be associated with, which may point me to the radiation sensor?).

Any hints on what wire does what in the cable feeding the servo? There are five feeding the device - white, blue, pink, purple, and red/orange (I'm guessing from memory at the moment). I don't have the LEXUS EWD pub but have the other 3 volumes. I'll hunt through them to see if there are wiring identifications.

Solar radiation sensor? Sheesh. Any intell on that you can provide would be great, too.

R,

Wm

[wwest]

When ignition key is on there is a noise coming from the area near the passenger footwell. The noise is like a mechanical cycling/clicking. I removed the small panel on the right side of the center console (2 each 1/4 turn fasteners) and the panel above the passenger footwell (disengage 3 each clips and disconnect power cable to LED illuminating the footwell).

Upon peering into the right side of the center console (laying in the front passenger footwell area) I could see the white plastic mechanism trying to turn with the airmix damper servo subassy driving it. I disconnected the power to the servo and the operation stopped.

How do I determine what is causing the servo to continue running?

(1) Is it getting a bad signal, i.e. position sensor not achieving the commanded position so it keeps running?

(2) Is the motor jammed/inoperable?

(3) Is the mechanism on the heater box jammed/inoperable?

(4) Other?

Are there error codes that would lead me to the answer? If so what are the codes and how do I access them? I have an OBDII scan tool but in searching this board it appears there's a way to get the climate control display to provide codes. If that's right where can I find the instructions on how to do that and the codes?

The servo is held to the heater box with 3 screws. The lower 2 are accessible, the 3rd is hidden behind an airduct that seems to be held in place with one bolt. Can I remove this bolt and hence that airduct to access the 3rd/hidden servo screw?

Thanks,

William

2004 RX330

20,500 miles (yes 20.5K miles)

Build Date 10/03

Easy question to answer...

The servomotor has an integral position feedback, a "potentiometer", variable resistor. With the connector disconnected from the servomotor/FB use a voltmeter to check if the servomotor drive voltage is still varying back and forth. If it is the problem is elsewhere, other wise the servomotor's internal position FB is questionable.

If it is only the passenger side reheat/remix servomotor doing the "clicking" then other than the servomotor assembly itself the passenger side solar radiation sensor is "suspect", next on the list.

Thanks for the prompt and informative response!

Another piece of info I forgot to add is that the noise will stop after being on some apparently random amount of time (i.e. I haven't resolved what that amount of time may be associated with, which may point me to the radiation sensor?).

Any hints on what wire does what in the cable feeding the servo? There are five feeding the device - white, blue, pink, purple, and red/orange (I'm guessing from memory at the moment). I don't have the LEXUS EWD pub but have the other 3 volumes. I'll hunt through them to see if there are wiring identifications.

Solar radiation sensor? Sheesh. Any intell on that you can provide would be great, too.

R,

Wm

The entire EWD, absent the "theory," is in the back of one of the standard Lexus shop/repair manuals.

[DIYAdvocate]

I also have a 2004 Lexus RX330 Japan built.  The passenger side air blend door servo was making a clicking sound at first.  After some time the clicking noise became a ratcheting noise that was quite loud and continued for long periods of time.  I removed the glove box and side panel so that I could see the servo actuator.  It was easy to identify the servo as the noise maker.  With the air conditioner on and the temperature set at 65 degrees the servo arm was in the down position.  As I changed the temperature setting (increasing) the servo arm did not move.  At 85 degrees setting the servo arm still did not move.  When I increased the temperature setting to HI the servo arm moved all the way to the top position.  I removed the servo motor and cleaned up the surface of the large gear pressed on to the servo arm.  It was very dirty.  Also, the worm gear had lifted up to a position that it would ratchet against the small gear (thus the loud noise).  Dorman makes a replacement servo motor.  You can find them on E-Bay and Amazon.  I installed the Dorman 604-902 servo motor in my vehicle.  There was no noise but the servo does not respond to temperature setting changes.  Same problem as the original.  Hope this information is of some use to you.

DIYAdvocate

[DIYAdvocate]

The servo motor will make noise intermittently at first.  It will last longer as time goes on.  The servo will make noise if the ignition switch is on even if the AC is off and the engine is has not been started.  I am also hearing some noise from the drivers side servo on my 2004 RX330.  I am not sure what I need to do next.  I am thinking that there is a control unit involved but I don't have a Service Manual to check it out.  I paid $83 for the Dorman replacement servo on Amazon.  If anyone knows whether there is a control unit in the center console, please let me know.  'Frogie' has a you tube video on how to clean up a servo motor.  It is well worth watching and it does work.