2018 IS350 F-Sport (I purchased new) 20K miles. I have a reoccurring issue with the HVAC system when it rains. 5 times now. First one was switching the vents to the windshield to defog during a driving rain storm. After I switched back to chest vents, I could get no A/C. Tried everything. I was actually on my way to the dealer for a service (90 mile drive) so they reinitialized the system--fixed.

I've had 3 others (before today) that have self remedied. all happened during a rainy drive.

Today, after driving in the rain, after shutting the car off, going inside and getting back in about an hour later, the system was totally shut down. No lights in the HVAC control panel. I went for a drive and got the system to boot back on. After I had been driving about 10 minutes and was pulling back into the garaged, I heard the sound of a flapper door operating in the dash (I had made no changes, this was spontaneous..) and now the passenger side gets no cold air, only the driver's side. I have shut off and restarted the car (X2) and run the system through all the off/on/heat/cool/dual, etc., etc. Can't get cold air out of passenger side vents (on recirc or fresh settings).

I know I have to take it to the dealer, but I'm feeling like there is a bigger issue than software here. A leak somewhere..?

Anyone have any similar experiences to share? I'd like to go to the dealer with more ammo than I have.

Thanks.

 

Lots of HVAC issues popping up... posted in this thread yesterday: https://www.clublexus.com/forums/is-...sues-160k.html

I had the same issue you are experiencing and I had to get the dealer to re-initialize the system to fix it. That was 1 year/15k miles ago and have had no issues since.

 

Sounds like it needs to be reinitialized again. I'm not suggesting that is a permanent fix, but can almost guarantee it will immediately fix the issue.
If you are getting A/C anywhere in the vehicle, then the system should be fully charged, with no leaks...if that's you meant by "a leak somewhere".
The dealer has access to a tech support line that can share if other vehicles has had similar issues (which they have had) and what the ultimate fix was...maybe replacing the HVAC box with the servo's and motors.

Let us know what happens.

 

Sorry I wasn’t clear about the leak. I meant a possible water leak into some electronic control of some sort as this has happened always during a rain event. I’m appointed at the dealer next weekend.

Thanks for the responses!

 

...and I meant to also say that the A/C out of working vents is cold/normal.

 

The issue isn't a leak for sure, cause you're not getting water inside the cabin anywhere.
It seems from those that have had the problem, that the issue is when they switch to Defrost, then switch to another mode, that's when things go south.
Now think of the times you use defrost...usually in rain or snow...no one drives around on a sunny day with Defrost on.

When you switch to Defrost basically all the outlet doors on the HVAC box close in order to direct maximum airflow at the windshield.
It seems like when it's time to change modes and some of those doors to open, something goes wrong and only some of the doors open.
Maybe it's a door that is slow to move cause it's tight, or something to that effect.

 

yes, I had exact issue. Re-initialization should fix it

 

A new development that I can now notice is that the A/C is not as cold as it was before. Switch from "vent" to "recirc" used to lower the temp pretty noticably. Now the cold air is definitely not as cold as before the failure. It's almost like the switch from recirc to fresh is also failing to work. The passenger vents (that don't flow cold air) are flowing heated air (tested this morning before sunrise, the outside air was much cooler than the passenger vent outflow).

Sasnuke, the first incident of this was exactly as you say. I switched to defrost and it was over. Dealer pulled code B1443. Reinitialized it and all was well.

pngo, we had the same event.

My concern is that this has reoccurred in 4 months and I don't want to keep having to trip the 90 miles to the nearest dealer. Since this F/U happened with no use of defrost-just "out of the blue", I'll ask more firmly that they check the whole system.

 

There are blend doors that control the temp of the air when you request it.
The fact that you have the A/C on doesn't guarantee that you will get cold air out of the vents...it only means the A/C system is active, the air blend doors still need to isolate the heat from the heater core and then provide you the cold air from the evaporator.
Think of it like using Defrost...when you switch to windshield Defrost, the A/C system turns on, but no one is going to select Defrost and a max cold temp at the same time...usually Defrost is activated with some degree of heat in the temp selection.
Right now the system is all over the map, so unexpected operation is the norm at this point. The reinitialization will put everything back in order, but that doesn't address the root cause of why it's happening...that's what the dealer needs to figure out.

 

Great explanation, thank you! My aim is to emphasize that "getting to the root cause" part.

Thanks again.

 

I'm not sure what's up with Lexus electronics lately but it's disheartening. But this is what I told people years ago.. when you start getting deep into the fancyelectronics game, these things happen. Gone are the days of dad's 2001 ES300 where everything lasted 2million miles.

Things are fancier in the past 15 or so years. My friend's 2IS 350 does not have working a/c either. he's been putting it off. I do miss old cars where it's just a switch you turn with your fingers and a simple on and off switch. New cars (not this one yet) use integrated fiber optics networking, fully integrated and interconnected modules that rely on eachother to work. Audi has moved to 24V system. Not to say I don't appreciate new tech. I definitely do. But gone are the simpler more robust systems we're used to. It's the way of the world now but i think car designers really need to work on making these systems more robust and less reliant on software glitches. I think it's the culture too.. not sure what's going in with the engineers who are designing these things but maybe it's younger culture who doesn't take pride in their work. i imagine now the people designing and programming these things are much younger than me and i know how young people work so it's kind of scary to think about. it's like a rat race where people don't take pride in their work, but jump ship to the highest bidder whenever the opportunity comes. Just a theory I have.

 

Update: car spent the day at Lexus of Wesley Chapel yesterday for diagnosis and treatment. Codes and investigation found the passenger side servo motor bad enough to warrant it's replacement. I requested that they look over the entire system (servos, harness, A/C amplifier, etc.) to try to diagnose the problem at it's cause, which they did. Reinitialized after the servo work and all is well at this point. It rained on the drive back (which has been the odd connector in these failures..) and as of the drive into the garage last night everything was good.

Service at Wesley Chapel was great.

Hopefully this is my last post on the subject. Thank you to all who replied here!

 

Drove to work this morning, A/C was fine. I picked up a coworker, and raised the temperature on his side a few degrees as it was pretty chilly in the car.
After I dropped him off, I turned the temp back down to LO both sides and now the driver's side chest vents blow hot air and the passenger's blow cold
This is the reverse of last week.
I can't get back to the dealer until Nov 11. The plan is to leave the car there for a few days to get it sorted out.
Frustrating. 250 mile round trip each time. Tough to keep this up, especially on a 2018 with 20K miles.

 

Damn...just damn!
The distance from the dealer isn't helping the issue either.
Assuming the air temp on the passenger side was as expected by the LO setting, maybe the driver's side servo has an issue as well.
I can feel for both sides...you want it fixed, and they want to fix it for you...but the problem is somewhat elusive.
Hang in there.
Update us in 2 weeks what happened.