Auto AC turns off at startup, resets to 75 when turned on (2 Viewers)

[beanTime]

Alright, I’ve seen this posted in some Land Cruiser and LS forums, but not in anything GX related. The GX cabin filter/blower area doesn’t have the actuated recirc door other Toyota cars have that seems to cause this issue when it’s forced open.

I got my 2016 premium a few days ago, I didn’t notice this when I picked it up but I noticed it now.

Basically when I start the car, the AUTO light is on but the AC system is off, I can’t turn it on or adjust anything. No air comes out, the fan is off, and the center display doesn’t show any temperatures.

After a minute or two, the AUTO light turns off and the whole AC system is off. I can hit the AUTO button to turn the AC system on, but it resets to 75 degrees every time. From here, the AC system works as expected, I can adjust the temperature, fan speed, it works fine. It just takes a while to get there.

This happens on cold starts. Interestingly, *sometimes* on warm starts, it’ll remember the previous settings and start up normally, kicking on the auto AC with the previous temperature a few seconds after starting the car. It resets on cold starts every time.

I checked the air filter and it looks fine, looks like the dealership replaced the filter really recently bc it looks brand new. Apart from that, not sure where to go. I don’t have access to techstream, apparently the servo motors can go bad but I have no way to check which one needs replacing (or how costly that will be?).

Tomorrow I’ll try power cycling the car by disconnecting and reconnecting the negative battery terminal, see if a good proverbial knock to the TV box kicks it back into shape.

 

[Acrad]

There are built in diagnostics as well

Post #108

#HVAC - #Air #Conditioning / #Heating - Troubleshooting, Questions, #Diagnostic - ClubLexus - Lexus Forum Discussion

GX - 2nd Gen (2010-2023) - #HVAC - #Air #Conditioning / #Heating - Troubleshooting, Questions, #Diagnostic - How can I control and ensure the kids stop messing with the rear climate settings. Toyota highlander and sequioa let's you. I have a 2014 GX Lux Thanks

www.clublexus.com

Code list on Post #109

 

[23GXOR]

Swap in a known good battery and see if that fixes it. I'm not suggesting it will, just offering the possibility. I've learned from years of owning European vehicles with temperamental electrical systems that when it comes to on-again, off-again electrical gremlins, especially ones that happen more on cold start than warm, battery issues are often the culprit.

 

[beanTime]

Thanks @Acrad !!

I ran diagnostic mode and it flashed code 41 on the center display, which maps to B1441, a fault with the passenger side Air Mix Damper Servo Motor Circuit. Correct me if I’m wrong, but that’s the servo that’s under the passenger side glove compartment on the side of the center console(???) I saw a 470 video where a guy had to take apart half the dash to get to one of the screws holding it in, apparently the whole thing has to come apart if you don’t have an angle driver. Scary.

I disconnected the negative battery terminal for an hour and a half or so, reconnected and started the car. Not surprisingly it did the whole reset thing and was at 75 when I manually turned it on. I ran diagnostic mode again and again it flashed “41”. I set my temperature preferences in auto mode, shut the engine off, then started it again (warm start) and it saved my AC settings.

Gonna try a cold start here in a few hours when I’m off work and see what happens, I will update the thread. Trying to give as much info as possible since this issue has not been documented for the 460 (at least not that I’ve found).

 

[beanTime]

Update: I cleared the AC code while on AC diagnostic mode by holding the front and rear refroster buttons. A few hours later I cold started the car and auto AC didn’t work as expected, it still resets every time.

Looks like I’m gonna have to replace that passenger side servo. Or maybe clean it?

 

[Acrad]

IMO…. You would likely have to take apart and replace servo motor. I’m sure someone has done that but can’t personally recall.

IIRC… disassembly shouldn’t be that invasive.

FSMs at the bottom of this post

Arch Stanton's 2013 GX460 premium & 2020 editions of 2010-2021 Lexus GX460 Repair Manuals

Hi guys, New to this community. I figured I'd introduce myself & my GX460. I'm not actually an off-road guy. I decided to join this community because I found more valuable information here than anywhere else when doing research for my GX460 purchase. I'm coming from the Volvo Swedespeed...

forum.ih8mud.com

 

[beanTime]

Update: I removed the bottom panel of the glove box to get a look under it to confirm where the passenger side servo is and what it looks like, finding the exact part number for it was surprisingly difficult. It’s part number 8710660230. The service manual should really have a part number glossary.

Also surprisingly, there are no YouTube videos or forum posts about removing the glove box and blower motor.

I looked through the service manual, it doesn't have a section dedicated specifically to the removal/replacement of that servo, but the process of removing the glove box and dashboard are sprinkled around in various places. I might try to do the repair myself because it's pretty simple, just tedious. I ordered the part from Bell Lexus and I'll update the thread from here as needed to document everything.

 

[beanTime]

FIXED

Did the repair today, it was a HUGE pain in the ass. Here's how it's done

First, you have to take out the glove box. Putting the steps for taking the passenger side of the dash apart and removing the glove box took a while. The service manual is basically a bunch of hyperlinks to the diagrams and graphics sprinkled all over the manual, so I took the liberty of stringing the steps together with details in this separate post.

Once the glove box is out, that's when the scary s*** starts. The servo is deep in the dash. I was hoping I wouldn't have to do any more removing of important stuff besides the glove box, but I was wrong. The servo is held in place by 3 screws as shown in this diagram from the service manual:

Here is what you'll see once the glove box is out:
Getting to that bottom screw is no problem, the bottom of the servo sticks out far enough that you can get it with a screwdriver or drill with a right angle driver adapter. The top left screw is a bit harder to access, it's probably possible to get in there and remove it without getting other stuff out of the way. The top right screw though, that one's a huge pain in the ass. It's up deep into the dash, and there's maybe a half inch of space between that screw and the air conditioning amplifier assembly, so the amplifier assembly has to come out. In order to get the amplifier out, you'll have to remove the passenger side footwear air duct.

Below is what you'll see. The passenger side footwell air duct is circled in red, the AC amplifier assembly is circled in blue, and the servo is just visible between them, pointed out by the yellow arrow.

Removing the footwell air duct: the air duct is held in place by one bolt near the blower and two little claw clips up where it connects to the AC unit, indicated in red below. The bolt is easy to remove, it's right there, but the two clips SUCKED, especially the back one. You have to get a flathead screwdriver under the claw clip thing to disconnect them then the duct comes out. Getting the flathead under the back claw clip sucked because you can't see it, you just kinda have to feel around with it until you get it. The front one is easy. Below, the back duct is circled in red and the front one is pointed at by the red arrow. So yeah, remove the bolt, undo the two claw clips, the duct comes right out.

Removing the AC amplifier assembly: This one is much more straight forward. There are a bunch of connectors that hook up to the amplifier assembly, remove those carefully. There are two nuts at the top of the assembly (red circle and arrow at the top) and one screw at the bottom (red arrow at the bottom). Remove those, and the amplifier assembly comes right out once the footwell duct is out of the way.

Removing the servo: Once the footwell air duct and AC amplifier assembly are both out, you have easy access to the servo. Remove the 3 screws and pull it out. There's some cable management connected to the servo, I just used pliers to pop it out. Do that carefully lol.

It's easy money from there. Put the new servo in carefully, getting the grooves on the arms of the AC assembly to line up with the holes on the new servo was kind of a pain, but you'll get it. Put the AC amplifier back and reconnect everything, put the footwell duct back, and reinstall the glove box and all of the trim. This fixed my issue, now the AC comes on right away with my previous settings