Here's an odd one for you, or maybe it's not and I haven't seen anything posted about it. 16 IS350-F, 11K....Driving with the A/C on as I normally do this morning (Typical Central Florida humid morning) my windows start to fog so I flip the A/C over to the defrost (warm air to the windshield). Windows clear so I turn the A/C back on. Cant get any cold air out of the vents, just warm air. Shut off the car at the gas station and restart it, now I've got cold A/C on the passenger side and kind of room temperature/borderline warm out of the driver side vents. Doesn't matter if its in Dual or Independent A/C modes or Automatic, it gets the same result. Made an appointment at the dealer day after tomorrow (while I still have a dealer before the hurricane takes it out ) but figured I'd throw it out here in case I'm missing something. Its happened before using the defrost but after restart it ran normally, so that time I chalked it up to a simple glitch.

 

Perhaps there's a slow leak in the system and you are low on refrigerant... I believe you can buy your own self testing kit and do it at home for like around $30ish or so. But should be under warranty anyways since its only a '16 model year.

 

When you switched to Defrost, did you adjust the temperature to warm?
Switching to Defrost only directs the air at the windshield, and turns the A/C on (whether the A/C light is on or not). The temperature of the air is still dependent on what the temperature is set to.

 

Could be a leak or could use some AC pro

 

If the A/C is blowing cold on one side, the chance of a leak is almost impossible.
While it's Dual A/C, the reality is it's one A/C system. If there is a leak, it will effect both sides, not just one.

 

Thats exactly what I figured. When I turned on the defrost I set the temperature warm and correctly got warm air at the windshield. On reconfiguring for A/C, I reset the temperature to "Lo". Like I said, I got warm air initially (from the vents )until I shut down and restarted the engine. Now I've got ice cold on the Pax side but sorta room temp on the driver side (in Lo setting). I'm thinking it's a glitch with the plumbing somewhere in the A/C as you have to assume with the dual mode system we have that there are some complex doors and valves to make it all work in there. Car's warranted...going to let Lexus of Orlando deal with it.

 

intermittent ac is not a leak issue .

 

Almost guarantee that the mixing door in the evaporator box is screwing up...or the actuator that controls the door.

 

while you're right, that it should be one system, I've seen this behaviour on many bmws when refrigerant is low. It's not super cold on one side, but significantly different enough that it is definitely noticeable. I don't have much experience when it comes to lexus, but based on my past experiences with bmws, I wouldn't say it's impossible.

easy first step would be to check ac pressures. basic gauge usually comes with those red tek kits. Normal pressure when car is off should be somewhere in the 70-100 psi range depending on temperature outside.

i could be completely wrong haha, just my 2 cents.

 

Mine actually has this issue very often, but the fog disappear within seconds so i thought it's just the way it is with this car... I rarely use my A/C thou.

 

Did you toggle the re circulation and the outside air? sometimes i feel hot air from the outside air, and i switch it to recirc for a little bit then throw it back onto outside air and the hot air goes away for me

 

You're correct...based on system design it could happen...but rarely...hence why I said 'almost' impossible.
Taking into account all the information provided by the OP, especially him mentioning the system returning to normal operation after a key cycle on a previous event of this happening, it suggests the issue is mechanical and not low refrigerant.
It's also possible he could be having multiple issues...maybe in the past it was a mechanical issue, and now it's a refrigerant issue.
Good thing it's under warranty...looking forward to seeing what the resolution is.

 

go to your dealer and have them re-initialize your servo motor. for whatever reason they mess up sometimes on their own or from replacing the battery but you only have 11k so i doubt you've replaced it... either way i can guarantee you that will be your fix

 

Sure enough...took it to the dealer and it was a software/computer glitch that is apparently a known issue. The system that operates the many diverter doors in there to move the selected temperature air to the right place in the cabin whacked out temporarily. It was taken care of before I finished my coffee in the lounge by a reset with a laptop. The explanation from the advisor: "it happens, neither we nor Toyota knows exactly why"

 

Awesome...it's fixed. LelandLs6 nailed that one...sounds like he's been a victim.
I'll keep this in mind in case it happens.