SaeedSH

Hi Lexus Comunity...

I have a 2015 Is 350 F sport... It has been running perfect till today... When my wife noticed that the vents for the rear passengers are blowing hot air unlike the front vents which were nice and cool... I had some stuff on the floor of the car so I thought that I was blocking some intake vents but couldn't find any openings that could have been blocked... (Where are the intake vents anyway?) I tried changing fan modes... Feet, windshield... Etc, but it would either stop or blow hot air agian. So everything was fine apart from the rear vents' hot air situation ... Until I stopped for refueling and turned off the car... After starting up the AC was working and I could feel cold air blowing from somewhare, not the front vents or the feet... I Started changing modes again and I've come to realize that the windshield vents are the only ones blowing air, nice and cold.



No warning light or messages popped ⚠

Filter is clean and nice... The situation under the hood looks good, unless I was looking at the wrong place.


P.S. Sometimes when I start up the engine the wipers turn on for a few seconds and stop... Is this common? I don't think I have rain sensors in my car🤔
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Sasnuke

Welcome to the forum.
The fresh air intake is under the wipers, so that's how you get air into the cabin.
If the air only blows on the windshield, even after you change modes, then something if up with the HVAC box behind the dash, or a servo motor on the HVAC box.
And lastly, the wipers should not turn on when you start the car, definitely not normal.
Kinda sounds like you have some wiring issue.

Has anything been done the vehicle lately? i.e. accident repair, windshield replaced, etc.

SaeedSH

Yes the car has been repaired in the front left corner near the tire... More details regarding the wipers...sometimes when I startup the car the wipers will wipe three times and stop...the only happens when the engine starts, never happened when the ignition is on...

The AC on the other hand developed a new problem...I switched it to heat and now it won't switch back to cooling again. So I decided to have the car inspected... And the servo motors where not working for both passenger and driver... Because no parts where available, he disconnected the servo motors and manully opened the servo doors to let cool air and open up the front vents... They work but I don't dare touch the mode button now, until I buy new servo motors...
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I have two questions now...
1.Does the servo motor control both air blow mode and cooling and heating servo door? Or are they separate motors?

2. What is the part number for the servo? And how much does each one cost? Or is their a way to just fix them instead of having them replaced? They looked shiny and new

Much appreciated
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Sasnuke

There is definitely something up with the wipers for sure. It sounds almost like something is being grounded when you start the car causing the wipers to operate.
In reality the wiper switch inside the car is a ground switch. Depending on what position you set the switch, it grounds the appropriate circuit and the wipers operate as per that selection.
If one of the wires in the circuit is being grounded when the vehicle starts, then the wipers will operate accordingly, they won't know the ground signal was not from the switch on the column.
Or there is the possibility that something is wrong with the wiper motor.

As for the servos, there are several servo motors that control the dual HVAC system, the blend doors for hot and cold, and the mode doors for face/foot/defrost/etc.
So it may or may not be just one motor that needs replacement, although I would find it odd if several went out at once.
The motors will look shiny and new as they are inside the vehicle and not exposed to the elements...they usually fail internally, which you can't see from the outside.
Depending on which motor(s) need replacement, it can involve a lot of time to remove the dashboard and the HVAC box. It's something you definitely want to fix right the first time.

SaeedSH

Is there some kind of system which forces all servo motors to shut in case one fails?
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If so, is there a way to figure out which motor needs replacement? Car is not showing any codes or hints...

From searching around the web, there appear to be a total of 4 servo motors... See attached photo

Hopefully there is a way to figure out the bad servo motor because each one is $130+...🙄

Circled parts are the servo motors

Edit
There are actually a total of 6 motor servos

Sasnuke

Likely there are codes in the system, but the HVAC system has no warning light, so you won't know there are codes.
In order the retrieve the codes you will need the Techstream software and the codes will be found in the Body ECU (I'm pretty sure going from my memory).
That will identify which servo(s) are bad...likely it's only one.

The system doesn't necessary shut the other servos off if one fails, but depending on what the issue is, the other may seize to function.
Every time you start the vehicle the servos go through a self check. If everything is ok, the self check takes only seconds and is so quiet you usually won't hear it unless you're somewhere that complete devoid of sound and you're listening for it.
If a servo has an issue the self check takes longer as the ECU attempts to run the check again before giving up. This is when any codes will likely be set, and the system will function however it functions.

In order to figure out which servo(s) are bad, you will need to retrieve the codes, otherwise you'd just be guessing.

SaeedSH

Well that is great news.. I guess I don't have to replace every freaking servo motor!

I've heard of techstream... I was thinking if using it to relink my TPMS sensors but didn't even have time to download it or buy it not sure how you get it, architects don't have much spare time😅, however this a goid chance to learn a few things, what hardware do I need beside a laptop... If there is a thread regarding this please post link... Much appreciated

SaeedSH

Back again... so I did tbe check for my car and everyhting was well apart from the AC ECU... Which gave two codes
B1454 Air Outlet Damper Cool Control Servo Motor Circuit - Passenger Side
B1455 Air Outlet Damper FOOT/DEF Control Servo Motor Circuit - Driver Side

There was also another code about being unable to communicate with the parking sensors... Well, I thought F Sport models don't come with parking sensors.

Anyway, what I need to know is which servos do I need to buy? Looking up the code does not help as it only yields what it means for Toyota cars in general.

And the Lexus parts page lists all the servos with numbers... Servo 1, Servo 2, Servo 3...etc.

So close... Any help would be great... Also if you can tell us all how to figure what part is needed so to resolve a trouble code


Also, the codes were in the Air condition tab... The body menu had the parking sensors code
U0265 - Lost Communication With Park Assist Monitor Module

SaeedSH

Up...
Need a tiny bit of help