Thanks for the great writeup! 250 for both air mix and mode servo and my problem is solved! Looking forward to being able to defrost my windshield this winter!

 

Hello I just seen a real cool video by a guy named froggy in YouTube about the problem that we share.. he takes the servo off and opens it..I've found to start with the clips furthest from the plug..and inside attached to the shaft of the motor is a worm gear that had some play in it not allowing it to engage the gear. You can check it's real easy and it's a possible fix if your is like that. It's for an IS and I have an ES and it's the same servo. http://youtu.be/s9S5B1Dn3j4

 

This is WarVet369 and i have read quite a few verzions of NO heat and i be,eive that there has to be a thermo controled door at the heater core and it is not working properly.SO i am going in feet first or should i say hands first and find out where that door is and either unstick it or replace it,but, either way i am going to have heat this winter in my 99 LexusRX300.

Warvet369--At you later

 

Great post, and I just wanted to add a little followup on the Froggy video that BOMBSHOP posted.
This worked for me. I found the video very longwinded and thought he went a little overboard with everything.

For me, I checked the slop in the worm gear and there was a good bit of axial play.
I took the motor out, checked it by touching a 9 volt battery to the two input tabs (lines up perfect).
Once I knew motor was good, put it back in and used a flat head (actually I used a butter knife cause I was too lazy to go outside :P) leveraged against the motor housing to push the "key" forward so it was tight against the worm gear.

I was in a hurry so didn't take pictures, but I sketched it out. Hopefully this makes sense.

 

Just wanted to post my results/thoughts. Maybe it will help someone else.

My wife's car (2001 RX300) was making this annoying BUZZING/GRINDING sound. And there was no hot air.

To get to the servo:

1) Took off the bottom panel below the glove box.
2) Took off the 2 hex screws at the bottom and 2 screws at the top of the glove box.
3) Unfortunately, my glove box was tethered to the airbag cord. So I had to squeeze the tabs to release the small panel, pull it through, then rotate the panel to separate from the glove box. DO NOT UNPLUG THE CORD!!!!
4) Remove 3 screws on the white plastic "vent" on the left side.
5) Remove the panel below that (has a flat-head plastic screw/snap on it).

Trying to see if maybe the arm was just stuck:

Next, I detached the arm on the air mix servo from the other piece, and turned the air to HOT, then COLD, etc. The arm on the servo did NOT move. So, the other guy's suggestion wouldn't work for me. Although, his pics were GREAT!

So, I had to take the air mix servo out:

The bottom 2 screws weren't that bad. But that top screw behind the pipes was a PAIN IN THE BUTT!

I was able to get the screw partially out with a stubby screwdriver (#2 phillips). But then I had to use a small ratchet with a #1 phillips attached. Both were at an angle. And wow, what a pain. Maybe the 2001 model is a little harder than others? It wasn't easy.

Then I just detached the servo cable.

Here's a pic of the servo out with the ratchet that I used to get that screw the rest of the way out:



Then, I took the servo apart. Turns out I had the same issue where the motor was becoming separated from the worm gear.

You can see that here:





So, I just used a gear puller (I had bought one a couple of years ago to fix the actuator for the door lock), to pull the "key" down the shaft a little bit. I'd guess about 1/8th of an inch?

Here's what the gear puller looks like:





Once I pulled the "key" out, there's very little gap anymore. So, it's not going to come loose again.

Here's a pic of the fixed servo:




Notice the extra space between the motor and the key after if was fixed (sorry that the angles were different).

Anyway, I didn't try to clean any contacts, or add any grease or anything like that. Just fixed the gear/key gap.

Everything works now. Servo arm moves all the way up (HOT) and all the way down (COLD). And the NOISE IS GONE.

Thanks to everyone for the info!

 

thanks for this... this worked like a dream... the worm gear on mine was still attached to key on the shaft... but it was binding since there was a gap on the top... so i moved everything snug up and now it works perfectly... saved me a few hundred from buying a new servo

 

Thanks a lot for the info

 

Thanks for the precise info and laymen layout of the actuator.The knowledge you shared saved me hundreds of dollars!!! Thanks " Cacophony"

 

Im starting to wonder if this is my issue as well because when it was cooler here(yes it can get cool here during the winter months despite it being a desert) I wanted heat; and it seemed like i was getting very little warm air out of the floor vents to the point i would have to to turn it up to like at least 80 or higher to get warm air out. Even though its getting to the time of year here where ya dont really need heat; still Im just starting to wonder if it this is my issue also. I may just take the glove box off and check the operation of the servos to see if they are both working properly. But then again i may just wait til the fall again when it starts to get cooler again(hopefully anyway)

 

Anyone know how I can get the 2 top screws that hold the glove box in place off because no matter how much force i tried with a philips screwdriver; I could not get the 2 top screws out. So whats the best way to attack this?

 

Can't imagine what the problem is. There is nothing special about those screws.
Once unscrewed you have to tug a bit to unseat the top of the glovebox.

 

Well; like i mentioned; I cant get the top 2 screws out for the life of me. I mean it almost seems as if someone used red loctite on the srews. Should i try a heat gun on the screws to expand the metal and see if that might help loosen them?

 

Red loctite wouldn't prevent unscrewing them. Just keep them from vibrating loose.
A heat gun would probably wreck the plastic dash.
Maybe try tapping the back of the screwdriver with a hammer.

Are you really unable to turn them? I would think if they were frozen you would have destroyed the screw heads trying to unscrew them.

 

Yes; I am definitely unable to turn both top screws. I tried with a ordinary phllips screw driver and got nowhere with it. As far as the red loctite goes; actually it can prevent screws from being turned if it sits there long enough and even if it doesnt. The red stuff is supposed to prevent screws from being undone easily as well. On another note; I did the auto plus recirc buttons while turning the ignition on and I got a 21 code. The ? is what is that pointing to?

 

maybe an impact screwdriver will help..they are a few bux at harbor freight. Helps with really stuck screws because they are spring loaded.