DIY Repairing Air Mix Servomotors
08-17-12, 06:05 PM
#47
After cleaning and testing the air/mix servo, has anyone ever experienced a situation where the servo does not move for all the degree changes. Mine gets to about 72 degrees and stops moving when I adjust the temperature lower. What I have also noticed is a sizeable movement from "Hot" to 85 degrees (the next temperature setting. Instead of moving incrementally from "Hot" to 85 degrees it moves quite a bit. I think the extra distance it's traveling is causing the problem. Is something wrong with the potentiometer? Any ideas.
08-18-12, 08:11 AM
#49
08-27-12, 09:27 PM
#50
Lexus Test Driver
BEST THREAD EVER.
Had this same issue with my 2003 ES300....annoying rattle behind the passenger side dashboard and climate control temp operation for the passenger side was wonky (would be slightly off from driver's side).
Followed instructions from this thread to clean grease off the potentiometer/gear/contacts..they had tons of contaminated grease on them..also removed the motor and applied adhesive to the worm gear because it was loose on the motor shaft, applied existing grease to the driven gears and reassembled everything - broke two of the tabs on the casing and glued them back on - and IT WORKS LIKE A CHARM!!!!!!!!!!
No more noise, operation is normal again. Thank God for this thread!
The servo was kind of a pain to get in and out but the fix was simple.
List price on the servo was $178.00!
Had this same issue with my 2003 ES300....annoying rattle behind the passenger side dashboard and climate control temp operation for the passenger side was wonky (would be slightly off from driver's side).
Followed instructions from this thread to clean grease off the potentiometer/gear/contacts..they had tons of contaminated grease on them..also removed the motor and applied adhesive to the worm gear because it was loose on the motor shaft, applied existing grease to the driven gears and reassembled everything - broke two of the tabs on the casing and glued them back on - and IT WORKS LIKE A CHARM!!!!!!!!!!
No more noise, operation is normal again. Thank God for this thread!
The servo was kind of a pain to get in and out but the fix was simple.
List price on the servo was $178.00!
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dosik2 (07-02-22)
10-05-12, 03:39 PM
#52
Driver School Candidate
RX300 Servo Motor replacement with PICS
I have saved a boat-load of benjamins with the help of this site ... thought I would return the favor. Here is a step-by-step instructions for removing servomotor (s) from a 1st generation RX.
Part 1.
1. With your hands, remove panel underneath glove compartment
2. With a 10mm socket remove the two bolts below the glove compartment door.
3. Open glove compartment, with #2 Phillips screwdriver remove the two screws located in the top corners.
4. Pull out the glove compartment with your hands. There will be a yellow bundle of cables that needs to be detached in order to move the glove compartment out of the way.
Part 1.
1. With your hands, remove panel underneath glove compartment
2. With a 10mm socket remove the two bolts below the glove compartment door.
3. Open glove compartment, with #2 Phillips screwdriver remove the two screws located in the top corners.
4. Pull out the glove compartment with your hands. There will be a yellow bundle of cables that needs to be detached in order to move the glove compartment out of the way.
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Measured (10-06-17)
10-05-12, 04:20 PM
#53
Driver School Candidate
RX300 Servo Motor repair/replace
Part II
***BONUS*** take this time to replace your cabin air filter - I found a mouse nest in mine...nice
5. With a flat-head screwdriver, turn the panel screw counter clockwise, then remove the panel that is under the center console by the passengers feet, by pulling the end closest to the engine. Sorry - no pic.
6. With a #1 Phillips screwdriver, remove the three screws attaching the white plastic air vent (see RED marks in pic for locations of screws - 1 is loose, 1 is remove, 1 is hidden)
7. TAKE SOME DECENT QUALITY PICS OF THE SERVO MOTORS and THEIR CONTROL ARMS - note the position of the control arms (SEE RED IN ATTACHED PIC)
8. TURN THE INGITION KEY TWICE AND NOTE WHAT SETTING THE AIR IS SET TO (ie. foot, foot and head, front defrost, or front defrost and foot) - 7& 8 are important for reinstallation
9. With a #1 Phillips screwdriver (stubby and/or screwdriver attached to ratchet are needed), remove the screws holding the first servo motor (locations noted in RED) - the backmost screw is partially behind the heating/cooling tubes...you must push in hard on your screwdriver while turning otherwise it is easy to strip the head
***BONUS*** take this time to replace your cabin air filter - I found a mouse nest in mine...nice
5. With a flat-head screwdriver, turn the panel screw counter clockwise, then remove the panel that is under the center console by the passengers feet, by pulling the end closest to the engine. Sorry - no pic.
6. With a #1 Phillips screwdriver, remove the three screws attaching the white plastic air vent (see RED marks in pic for locations of screws - 1 is loose, 1 is remove, 1 is hidden)
7. TAKE SOME DECENT QUALITY PICS OF THE SERVO MOTORS and THEIR CONTROL ARMS - note the position of the control arms (SEE RED IN ATTACHED PIC)
8. TURN THE INGITION KEY TWICE AND NOTE WHAT SETTING THE AIR IS SET TO (ie. foot, foot and head, front defrost, or front defrost and foot) - 7& 8 are important for reinstallation
9. With a #1 Phillips screwdriver (stubby and/or screwdriver attached to ratchet are needed), remove the screws holding the first servo motor (locations noted in RED) - the backmost screw is partially behind the heating/cooling tubes...you must push in hard on your screwdriver while turning otherwise it is easy to strip the head
Last edited by jcorava; 10-05-12 at 05:44 PM.
10-05-12, 04:42 PM
#54
Driver School Candidate
RX300 Servo Motor Remove/Repair/Replace
Part III
10. Remove the first servo - TAKE A PIC FROM THE BACK - and note the position of the control arm (RED) relative to the body of the servo (GREEN) - you want to make sure you reassemble (assuming you are doing a repair) in the same position - disconnect leads from top of servo
11. Pry open the servo - NOTE: pry tabs are fragile - most of mine broke when using a screwdriver (Sorry NO PIC)
12. Clean copper contacts and wheel with a Q-Tip and rubbing alcohol
13. Apply Dielectric grease to copper contacts and wheel (Sorry - no pic - same spot as was just cleaned)
14. NOTE: not sure if this is important - but probably a good idea to note the position of the motor before you remove from the servo so the leads do not get reversed
15. NOTE: screw gear has a notch - this needs to be seated onto the shaft of the motor
10. Remove the first servo - TAKE A PIC FROM THE BACK - and note the position of the control arm (RED) relative to the body of the servo (GREEN) - you want to make sure you reassemble (assuming you are doing a repair) in the same position - disconnect leads from top of servo
11. Pry open the servo - NOTE: pry tabs are fragile - most of mine broke when using a screwdriver (Sorry NO PIC)
12. Clean copper contacts and wheel with a Q-Tip and rubbing alcohol
13. Apply Dielectric grease to copper contacts and wheel (Sorry - no pic - same spot as was just cleaned)
14. NOTE: not sure if this is important - but probably a good idea to note the position of the motor before you remove from the servo so the leads do not get reversed
15. NOTE: screw gear has a notch - this needs to be seated onto the shaft of the motor
10-05-12, 04:56 PM
#55
Driver School Candidate
RX300 Servo Motor Remove/Repair/Replace
Part IV
16. Remove lead from 2nd servo
17. Remove upper screw (RED circle) with #1 Phillips screwdriver and lower screw (RED arrow) with #1 Phillips screwdriver - NOTE: this screw is partially hidden behind the heating cooling tubes - need to push the screwdriver HARD then twist otherwise easy to strip the head
18. Remove rear screw - need to crawl in to see this one - good news is there is a little more room so a longer #1 Phillips screwdriver should fit
19. Remove the servo and as with the other servo TAKE A PIC of the location of the control arm BEFORE you pry open
20. Clean contacts and contact wheel and regrease as you did with other servo.
16. Remove lead from 2nd servo
17. Remove upper screw (RED circle) with #1 Phillips screwdriver and lower screw (RED arrow) with #1 Phillips screwdriver - NOTE: this screw is partially hidden behind the heating cooling tubes - need to push the screwdriver HARD then twist otherwise easy to strip the head
18. Remove rear screw - need to crawl in to see this one - good news is there is a little more room so a longer #1 Phillips screwdriver should fit
19. Remove the servo and as with the other servo TAKE A PIC of the location of the control arm BEFORE you pry open
20. Clean contacts and contact wheel and regrease as you did with other servo.
Last edited by jcorava; 10-05-12 at 05:09 PM. Reason: forgot image
10-05-12, 05:37 PM
#56
Driver School Candidate
RX300 Servo Motor Remove/Repair/Replace
Part V
21. Reinstall the lower servo - note in the attached pic - the control arm of the servo has a metal pin sticking out - this pin needs to seat into the slot on the arm that is connected to the car (RED arrow)
22. Reinstall the upper servo - same attached pic - the control arm of this servo also has a metal pin that must seat into its corresponding slot (BLUE arrow) ... in addition, there is a pin attached to the metal arm (GREEN arrow) that is attached to the car - this pin must seat into the slot in the control arm of the servo
23. Connect lead wires and tighten all screws.
23. Turn ignition key two spots - check that fan is working and mode can change from feet to head to front defrost
NOTE: if the control arms are in the wrong location, then the computer will not let the mode change - I had this problem - took me a while to figure it out - in order to avoid my mistake, note the mode setting of the fan before you start the work and do not change this setting ... further note the positions of the control arms BEFORE you pry the servos open.
24. Reconnect white plastic air vent with the 3 screws
25. Reattach panel ... Reinsert cabin airfilter...Reinstall glove compartment...
If this solves your problem as it did mine, you just saved approximately $300 in parts and who knows how much in labor
21. Reinstall the lower servo - note in the attached pic - the control arm of the servo has a metal pin sticking out - this pin needs to seat into the slot on the arm that is connected to the car (RED arrow)
22. Reinstall the upper servo - same attached pic - the control arm of this servo also has a metal pin that must seat into its corresponding slot (BLUE arrow) ... in addition, there is a pin attached to the metal arm (GREEN arrow) that is attached to the car - this pin must seat into the slot in the control arm of the servo
23. Connect lead wires and tighten all screws.
23. Turn ignition key two spots - check that fan is working and mode can change from feet to head to front defrost
NOTE: if the control arms are in the wrong location, then the computer will not let the mode change - I had this problem - took me a while to figure it out - in order to avoid my mistake, note the mode setting of the fan before you start the work and do not change this setting ... further note the positions of the control arms BEFORE you pry the servos open.
24. Reconnect white plastic air vent with the 3 screws
25. Reattach panel ... Reinsert cabin airfilter...Reinstall glove compartment...
If this solves your problem as it did mine, you just saved approximately $300 in parts and who knows how much in labor
10-08-12, 06:08 AM
#59
Driver School Candidate
RX300 Servo Motor Remove/Repair/Replace
The top servo controls the vents that receive air - so if you request air only at your feet, but it is coming out at your head and/or the front windshield, then I would service/replace this unit.
Having said than, in my car ('02 RX300 with 171,000 miles) the air system was working fine, but there was a sound coming from the center console area -best way I can describe the noise is "gerbil running around in a can." Given the price of these units, I decided to attempt to service them first - so, I removed both of my servo motors, opened them, cleaned all contact points and applied fresh dielectric grease. Currently, my noise is gone. I did not see anything out of place (i.e. skipping gears) just dirty contacts).
Here is a URL for a YouTube video that shows the upper servo motor failing. I think having a look like this guy did is a good idea, especially if your car is making this kind of noise. BTW - this in not the noise my car was making - FWIW.
Last edited by jcorava; 10-08-12 at 06:25 AM.
