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Heater blowing cold air

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Old 07-24-14, 08:29 PM   #76
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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!
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Old 09-22-14, 06:17 PM   #77
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Default possible fix

Originally Posted by RX300malib View Post
So there’s someone else out there with funny temperature issues. I have written in the past regarding the NO HEAT to the drivers side only which is still an issue as winter is upon us here in Conn.

1. If you remove the glove box you can visually see the servos and adjust ***** to see them in action. You can see the servo move the vent door for the heat and adjust the defrost/dash vent/floor board direction diverter.

2. Note the vent behind the glove for the inside/outside air input which is servo 3 of 3.

3. In my 99 model there is a temp sensor just infron of my right knee when driving the vehicle. If you remove the lower panel, you can remove the unit and notice the fan speed change as mine did which I assumed meant it was working.

To this day I have no heat crossing over from the heater box to the driver side which is a pain in the butt. So, I had to be creative a provided a flex hose from the passenger side foot vent and crossed it under the air box over to the driver side foot area. Now my feetsies don't freeze in the way to work.

I suspect that there is a vent door fault inside the air box and I have no plans to remove the entire dashboard in order to investigate or pay the crazy price to replace. I have a 99RX with 180K mile and runs like a champ. Yes the tranny was replaced at 125K.
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
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Old 10-09-14, 07:41 PM   #78
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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.

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Old 10-20-14, 07:05 PM   #79
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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.
Click the image to open in full size.
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Old 11-03-14, 02:27 PM   #80
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Default Another successful fix!

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:

Click the image to open in full size.

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:

Click the image to open in full size.

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:

Click the image to open in full size.

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:

Click the image to open in full size.

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!

Last edited by Cacophony; 11-03-14 at 02:37 PM..
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Old 02-17-15, 11:44 AM   #81
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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
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Old 02-17-15, 11:44 AM

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