NickDangr

I'm afraid that my reports are changing because I started with what my girlfriend told me about riding in the back seat. Then I did my own investigation to get more details, and I'm finding something different.

It is a luxury model with three-way.

I did some experimentation today. S-Flow had been off, so there should have been air flow in back. As I continued to cycle through settings, the air flow seemed to get better. I started to feel warm air under the front seat. Maybe a door was sticking.

But I am suspicious of the servo motors. Even with the fan speed on high, the flow through the back console vent is much less than the dashboard vents. Is that normal?

Thank you all for telling me about S-Flow. I didn't know what that button did.

CottageChz

I suspect servos at this point as well, though it sounds like you need to do some more testing.

Glad I could help provide some info on S Flow even though I overlooked other relevant info in your original post, as @jgscott pointed out ​​​​​​​

Mangsailor

The rear vents will pour air out of them if 3-zone mode is off, and S-flow is off with an empty rear seat, if full-face is selected for the air vents. So, no floor, no defrost, just face.

Does it blow significantly more air out than it did before like this?

NickDangr

Not significantly more, no. It's changed from a trickle to a light breeze, while the dashboard vents are moving a lot of air.

I'm supposed to turn 3-zone off to warm the back seat passenger? I'll have to experiment some more.

Mangsailor

No, that's not what you have to do....

I wanted you to turn it off so the rear unit was not being independently controlled and trying to mix a temperature or play with anything else. If you have your HVAC in Auto mode, and then change your vent setting (face/floor/etc) the fan also stays in auto. Idk what other things 3-zone would override if the front driver was adjusting fan speeds or etc if the rear had its own zone, which is why I advised you make sure it was off if you're trying to feel the vents and come to a conclusion.

I have an air-speed measuring gizmo that I can grab some data with. Kid's sick with the flu so it'll be a while before I can write it all down.

NickDangr

I used the rear heat again tonight. I ran the fan at max speed through the dashboard vents. There wasn't much air flow through the console vent. But after a few minutes, there was good air flow. I returned the setting to Auto, and the air flow continued. I'm leaning towards a sticking door or a lazy servo motor.

After half an hour, the sides of the console next to the driver seat and passenger seat was quite warm. Is that normal? Is there an air leak blowing hot air against those walls?

bclexus

jgscott

iTrader: (1)

I sat in my 13 Lux with 3 way yesterday parked in the garage. I ran all the different setting of S-Flow, no S-Flow, floor only, floor + vent mixed rear air, 3 way, and so on. I also sat in the back seat and used the back seat armrest controls for rear passengers temp adjustment. Whatever I set ran as it was designed to do. I never had the problem you have with either running Heat or cold a/c. All vents and settings all worked as expected.

I did have my Servos Calibration software updated by Lexus dealer about 2 years ago under the Lexus Customer support program. They just did it, and I was Not having a problem then either. One thing while in the back seat yesterday I got to thinking about is? WHAT is your back seat individual Temp controls set at on the displays in the back Armrest?????? If you don't find a "ah ha" fix with your settings? It's your Servo Motors. Techstream Recalibration is the only shot you have, beside step 2, if TS Calibration does not work. Step 2 would be the well known famous SERVO Problems that are very, very likely and common.

https://www.clublexus.com/forums/gs-...ll-notice.html

NickDangr

Unfortunately, the recall for my car expired January 2022. I didn't think I had a problem then.