gazi001

I cleaned the both mode and airmix servos for noises and reinstalled. I checked servo arms are moving by key on and push ac/heat and mode button before I disconnect.
Now after installation the mode servo's arm went all the way up when I turn the AC on working fine cold air no noise but only one mode. No other modes working like floor, defrost etc. Airmix servo's arm stay down cold but doesnot goes up for heat if I turn the heat. Everything was working fine except noises before. Only thing I forgot to add Dieelectric grease on the surface of servo. Should I reinstall them? It was very hard to open the top screw of air mix servo.

code58

How did you clean the metal surfaces in the servo? Did you just clean the grease off and not use anything abrasive on it? Don't use dialectric grease on the contact surfaces, it's NON-conductive and will not allow the juice to flow. Use a grease that IS conductive.
Also, the screw that is hard to get to on the one servo is much easier if you use a #1 Phillips screwdriver on an angle (it kind of works like a universal joint that way).
One last thing, are you sure you got the arm in the right relationship when you reinstalled the parts in the servo?

gazi001

Yes. I clean the surface with alcohol and q-tips and grease off and no abrasive on it. I think the arm goes in right relationship otherwise it shouldn't fit. But I am not sure. After I removed the servo motors from the linkage didnot mark the positions of white arms. I opened the servo motors and clean it and snap together. The arms moved from the original position after I open the servo for cleaning. Does it necessary to add grease? Let say the original position of arms moved and is there anyway to reset it?

gazi001

Code58, I found the pics of mode servo motor position in Lexus repair manual. If I turn the key on, press the ac on and mode to face. Key off remove the motor again and follow the picture for arm up position. Reassembled the servo and reinstall the servo motor again. Should the arm will be in right relationship again? Here is the pdf pic.

code58

Gazi- it's been a while since i've done one of those but I'm pretty sure you have to have things in proper position when you put it back together or it won't work right. It should be taken apart and greased also or there will be excessive wear on the contact strips. be sure and use a grease that is conductive, NOT non conductive. The parts house where you get your parts should be able to supply the right stuff. Be sure they know what they're talking about and weren't just flipping burgers last week. You shouldn't have to reinstall the servo to tell if it's right. You should be able to just use the pictures you posted to reference that. Be sure you use the picture for L. hand drive and I think the pictures are from the BACK side, not the front side that you see when you're taking it off. Double check that. You should be able to just plug it in and hold it in your hand when you change mode to check that it's in the right position. (according to the picture).

gazi001

Thanks Code58 I will try this week.

reisjdmd

code58
i'm in the process of removing and replacing the air mix servo on my 99 rx300. can you please explain what you mean by saying the arm has to be positoned properly?? is it not enough to just install the new unit and allow the track to be guided by the new arrm??? what am i missing here??

salimshah

When you replace the servo, you will force the duct arms/levers to match up with the condition the servo is in. You should be fine in simply replacing the servo.

During servo assembly (manufacturing) the arms are positioned properly with respect to the rotating switch inside the assembly. Read that as extreme positions of the arm is in concurrence with the extreme position of switch (driven by the gear) inside the servo motor.

Problem:
Now if some one reassembles the servo (position of the arm does not match with the spinning gear switch) then the arm travel will be different. The key is to match up the switch (position of the contact gear) with the proper position of the arm. One work around is to figure out the limits of travel of the arm and the switch and do a best guess in the middle for both. With the attached diagram one can guess at the halfway point of the arm [or the max travel]. [Pretty hairy] It is very important to mark the position of the arm arm and the switch-gear.

I hope code does a better job explaining.

Salim

gazi001

Thanks Salim. Finaly just now 11:35pm I got the mode servo arm in the right relationship. Now it works perfect. No noise and checked the arm is moving and follow the mode face to leg.

code58

If you are installing a NEW servo, just simply install it. The point at which you have to have it in the right position is when you have taken the OLD one apart to clean the contact strips and grease it. With a new one, it's been put together in the right relationship in the factory so no need to worry. Read Gazi's post above mine to see why it must be marked when taken apart and reinstalled in the same position (or relationship internally).

reisjdmd

thanks to all for clearing that up. i have one last question. i have 2 screws removed from the ac servo, and i have the PITA screw about 1/2 removed, by using a right angle phillips head screwdriver [i took a straight one and did a very sharp small 90 degree bend using my map/oxygen torch]. yesterday i bought a stubby phillips head screwdriver. tonight i will try to finish removal. here is my question: does the stubby head fit between the two aluminum tubes??? if not, i cannot for the life of me see how stubby head makes removal easier. any advice appreciated, as i am almost there, having only the last half of the screw to remove. good lord, that is a tight fit!!!!!

also, i have the following idea regarding the PITA screw. what if i JB WELD a small nut to the head of the phillips head screw. then i should be able to use a small open end wrench to re-install, or to remove, again, if necessary. does that make sense???

or i could use a dremel cutting wheel to cut a pair of right angle slots into the screw head. i would prefer that over the phillips head for such a very tight fit.

salimshah

Few words and well stated. I should have waited and not jumped in.

Salim
.

salimshah

Just trying to make sure you are dealing with the right servo.... the mode servo is higher up and the mix servo id closer to the floor (the aluminum tubes run in front of the screw head.

One solution fits all will not work as it depends upon how the pipes are connected. Few things would help:
1. Always start by undoing the difficult screw. The other screws will hold the piece in place.
2. Phillips head screws require lot of pressure down on the head so an angled device can strip the head.
3. You can replace any screw with the other type .. just make sure the length and diameter and the threads are the same. I just go through my bin of old stuff and get a close match.
4. HarborFreight sells a cheap ratcheting low profile drive set. Once you have broken the bind (which you have) it can do the rest (again space permitting). Item #92630
5. When you reassemble, try to screw down the difficult screw last. If you are worried that it can work its way out, use a dab of finger nail polish at the edge.

Salim

gazi001

For the airmix servo motor has one very difficult screw behind the two heater core pipe. I used precision screw driver between the pipe and moved with small noise pryer. Remember to pull the first pipe little bit toward you hold for make space to fit in and move the screw driver. Once it open little bit then easy and will come off. Good luck with you. Make sure you mark the arm position or take a picture for remember. Don't make a mistake like I did.

gazi001

Stuby screw driver doesnot fit between pipes. if the size is 1.5 or 2 mm and lentgh should be 2.5 inches or more.