Rear ceiling vents turned off randomly (1 Viewer)

Joined
Nov 28, 2020
Messages
751
Location
central florida
2011 lx570 200 series

My 1 year old was playing with buttons in the front seat and now the rear ceiling ac vents do not blow.might be a coincidence or maybe she pressed some buttons and told the vehicle to do this…

There are like 60 buttons on the dash and I’ve messed with all the ones that one might reasonably expect could turn on or off the rear vents.

Is there a specific button or menu that controls the rear ceiling vents?

Are our vehicles equipped with some archaic version of Lexus’s “s flow” system (video at around 1:45 attached) which turns off vents if it doesn’t sense a person sitting there?

When I turn on the cool box it blows ice cold.
Rear center console vents blow cold.
Checked fuse 18 under the hood which supposedly controls rear ac fan and it’s good.

Free on/refrigerant was at 28 psi at 93 degrees ambient so I bumped it to 31 psi.

The ceiling vents won’t turn on though the ac is blowing extra cold. They were blowing strong earlier in the week-ive got a car seat back there and it would blow the kids hair around.

Does anyone have any ideas? I think it’s done this before and I don’t know what I did to fix it. I remember all of a sudden the ceiling vents started blowing randomly. No idea why.

I’ve already tried unplugging the battery for a minute or two, checking the fuse, and bumping up the free on.

Update: the ceiling vents started working again the next day for some reason. This is the 2nd time it’s happened. Still no idea why.

Update 2: they wouldn’t turn on again in the afternoon at around ambient temperature 93 degrees. Starting to suspect it’s a free on issue and that the truck “sacrifices” the ceiling evap when there’s not enough free on to get it cold. Will see if it turns on again when it’s a bit cooler outside.

 
Last edited:

LvCruiserNewb

SILVER Star
Joined
Jan 6, 2019
Messages
51
Location
Vegas
I dont know what other controls are in a 2011 LX but I know on my 18 LC there are separate rear controls on the back of the center console. When the kids mess with them it plays havoc. Specifically the rear mode selector button has no way for the front controls to override it or change it. I can change the rear temp and fan speed from the front but when the rear control changes the air vent mode (floor, high, both) Selection it can only be fixed from the rear control. I can't count the times my kids feet have kicked that switch and ended up selecting the floor position for airflow then complained to me they weren't getting any air on them from the rear vents.

20220626_081457.jpg
 
Joined
Nov 28, 2020
Messages
751
Location
central florida
I dont know what other controls are in a 2011 LX but I know on my 18 LC there are separate rear controls on the back of the center console. When the kids mess with them it plays havoc. Specifically the rear mode selector button has no way for the front controls to override it or change it. I can change the rear temp and fan speed from the front but when the rear control changes the air vent mode (floor, high, both) Selection it can only be fixed from the rear control. I can't count the times my kids feet have kicked that switch and ended up selecting the floor position for airflow then complained to me they weren't getting any air on them from the rear vents.

View attachment 3043449
Thanks ive messed with those buttons quite a bit, can’t seem to get air to come out at the feet or the roof…just the center console.

I’m starting to think maybe the overall free on level is low, however I cannot find what the proper psi is that the low side should have.
 

CSteppe82

SILVER Star
Joined
Dec 18, 2011
Messages
450
Location
Birmingham,Al
Website
www.instagram.com
Thanks ive messed with those buttons quite a bit, can’t seem to get air to come out at the feet or the roof…just the center console.

I’m starting to think maybe the overall free on level is low, however I cannot find what the proper psi is that the low side should have.
I’ve had the same issue on my 08 and it was low on Freon.
 
Joined
Nov 28, 2020
Messages
751
Location
central florida
Joined
Nov 28, 2020
Messages
751
Location
central florida
No clue. I took it to my mechanic.
As an update for anyone else that comes across this thread looking for a solution:
I bumped my running Freon level from 28 psi up to 31 psi
-The next day the ceiling vents started working when it was 77 degrees out in the morning…rear ceiling vents blew kind of warm when it was 91 degrees out.
-5 days later tear ceiling vents were still working.
-1 full week after that mild recharge, rear ceiling vents work fine in the morning at around 77 ambient temp but then do no turn on in the afternoon at around 90.
-8 days after mild recharge, rear ceiling vents don’t turn on in the morning at 77 ambient temp.

Interestingly, even when I press the button to turn off the rear fan in the front driver seat area, it has no effect on the rear center console fan.

Does anyone know if the “rear fan” button in the front seat is supposed to control the rear ceiling vents?

Anyone know why the proper psi for the ac should be at various ambient temps?
 
Joined
Jul 3, 2008
Messages
4,010
Location
Illinois and Alaska
As an update for anyone else that comes across this thread looking for a solution:
I bumped my running Freon level from 28 psi up to 31 psi
-The next day the ceiling vents started working when it was 77 degrees out in the morning…rear ceiling vents blew kind of warm when it was 91 degrees out.
-5 days later tear ceiling vents were still working.
-1 full week after that mild recharge, rear ceiling vents work fine in the morning at around 77 ambient temp but then do no turn on in the afternoon at around 90.
-8 days after mild recharge, rear ceiling vents don’t turn on in the morning at 77 ambient temp.

Interestingly, even when I press the button to turn off the rear fan in the front driver seat area, it has no effect on the rear center console fan.

Does anyone know if the “rear fan” button in the front seat is supposed to control the rear ceiling vents?

Anyone know why the proper psi for the ac should be at various ambient temps?
The rear console vents are supplied from the front blower.
 
Joined
Nov 28, 2020
Messages
751
Location
central florida
Makes me wonder whether there is a short between the switch in the front and the rear ceiling fan in that case.
 
Joined
Nov 29, 2019
Messages
612
Location
Los Angeles
I’ve heard of weird things happening when the cabin temp sensors aren’t working. The system doesn’t sense that the cabin is too hot or too cool and can’t trigger the AC system to do its thing.
 
Joined
Nov 28, 2020
Messages
751
Location
central florida
I’ve heard of weird things happening when the cabin temp sensors aren’t working. The system doesn’t sense that the cabin is too hot or too cool and can’t trigger the AC system to do its thing.
Any idea where they’re located?
 
Joined
Nov 29, 2019
Messages
612
Location
Los Angeles
In my 17 they are a weird looking round plastic piece about the size of a half dollar near the cup holders in the rear quarter panel. And they have some slots in them.
 
Joined
Nov 28, 2020
Messages
751
Location
central florida
Turns out it was my rear blower motor.

Getting to the blower motor required removing the 3rd row seat on the driver side to access the ceiling vent blower motor which is behind the panel behind that seat.

When turning the rear fan on on the switch on the dash, it would click ever so quietly but not actually spin…then when you spin the blower motor with your finger slightly it would spoil up and blow nicely.

I need to order a rear blower motor and swap it out…might require another evacuation of the ac system since it appears Toyota designed the blower motor to only be replaced if you remove the entire assembly.

The part number for the rear blower motor appears to be 87103-28111. I think it’s the same for the land cruiser. You save a few dollars by purchasing the Toyota one rather than Lexus.
 
Last edited:

bloc

SILVER Star
Joined
Sep 19, 2008
Messages
10,050
Location
Central Texas
Anyone know why the proper psi for the ac should be at various ambient temps?

Gay Lussac’s law. It states that the pressure of a given amount of gas varies directly with the absolute temperature in a given container.

Put simply, for the gas portion of the refrigerant, if the temp rises so will the pressure.
 
Joined
Nov 28, 2020
Messages
751
Location
central florida
Gay Lussac’s law. It states that the pressure of a given amount of gas varies directly with the absolute temperature in a given container.

Put simply, for the gas portion of the refrigerant, if the temp rises so will the pressure.
Ended up being that I had also overcharged the system as well. It called for like 2.24 lbs and I had 3 lbs in there. Lesson learned: probably not a good idea to use those cheap refrigerant lines to get the refrigerant levels to a certain psi…better to get it all evacuated, measured, and then refilled.
 
Joined
Nov 28, 2020
Messages
751
Location
central florida
-The rear blower motor has the same part number whether Toyota or Lexus…you save like $10-$15 by buying Toyota.
-to get at it, you have to remove the 3rd row on the driver side and various paneling/plastic
-you’ll need to evacuate the refrigerant from the ac system and disconnect it at the bottom of the rear ac assembly
-you do not need to disconnect your coolant lines (that run the heat back there)
-you can pivot the ac assembly enough to get the blower motor/fan out without

00656653-2595-4A7D-9765-298335589B5C.jpeg


01ADEE34-DB6E-439F-A0C2-F607EB20BD8B.jpeg
 
Joined
Nov 28, 2020
Messages
751
Location
central florida
Is there a pre-filter?
Not that i saw. There is a formed felt “funnel”/cover (for lack of a better word) that bolts to the outside of the fan. It sort of grabs dust on its way into the fan inlet.
 

Users who are viewing this thread

Top Bottom