GS4IV

For over a year I am trying to get Lexus to solve a problem with my A/C heating system.
With outside temperatures below freezing, after warm up, my car is blowing cool air on driver side dash vents and hot air on passenger side.
This can be either in "Auto" or bilevel (face and feet mode) AC switch on or off - does not seem to matter.
Following was replaced or tried:
- servo motors
- electronic control unit
- sensors
I am close to the end of warranty and at this point the best advice I can get from Lexus is to switch to dual mode and adjust to equalize the temperature on both sides.
If you have had a problem like this or have some ideas I would appreciate hearing them

Alewifebp

I no longer have my 2000 GS3, but I had the exact same problem. It was more varied when it would happen, but the dealer was never able to replicate the problem, even after taking it back at least four times. I remember taking a long trip in the car when it was around 5 F outside and the car was freezing since cold air was coming out of the drivers side. I did seem like it was warmed at least a little bit, but it was cold no doubt. Had the problem for over a year. Turned the car in off lease without it getting fixed. Putting the temperature up helped a little bit, but did not solve the problem. Very frustrating.

GS4IV

Thanks for your reply - you are correct if you put the system in the dual mode it can be adjusted to give the same temperature both sides but as soon as put back to the "normal" the driver side goes cold.

LarryF

I have the same problem in my 2001 GS300, and remember reading a thread a while back (perhaps as long as 2 years ago) that several other people were experiencing the same thing. I asked my dealer about it a couple of times when the car was in for service, and they were never able to duplicate it. Actually, I normally notice it when the outside temperature is mid-range, and the dash vents are active and heat is being mixed with air conditioned air. I've never noticed it in very cold weather because all of the air is normally directed at the floor under those conditions. The last time I asked my dealer about it, they told me to estimate the temperature difference between the driver side and passenger side vents, and they were apparently going to recalibrate the system to compensate for the difference. To me, that wasn't a real fix for the problem, so I never followed-up.

GS4IV

I am glad to hear that this problem is not only in my imagination.
Larry if you change from auto mode to dash and foot vents you will be able to feel even more of the temperature difference even in freezing temperatures. The only change is that it will take a little longer to get to this point.
The heating ECU first stops all air flow to the cabin until the engine heats up, then it directs full hot air to the footwells only and eventually it either switches to face vents or footwells while lowering the temperature and air flow.
The dealers can not recalibrate any difference between the two sides they can only calibrate the overall temperature as related to the displayed temperature.
On my car if I go to dual mode setting and manually adjust the driver side to 2-3C (4-6F) degrees higher I can get about the same temperature from both sides.