I did a search, but got no real answer. I want to know why the driver's side gets cooler air than the passenger side. If I have it at 70, the passenger vent is much warmer, with no warm air coming out on my side. I'd put it on Dual, and I have to get it up to around 78 just for it to feel like 70 on the other one. Granted, if there is no one sitting in the passenger seat, I could just put it up to 78 anyway, but it bothers me that it's uneven, and others on this board have it happen too. My dealer told me they all do this, something about Lexus engineering, bla, bla, bla...meaning "I don't really know the answer, so I'll dazzle you with B.S." Does the seat sensor (for the seatbelt light and airbag) communicate with the climate control, and if so, wouldn't it direct heat to the driver, and cool air to the empty passenger area ? I don't know if this happens randomly, but when I do, it's extreme temperature-wise. Anyone ??

 

I've noticed this too...but not as extreme as your case. Only a few degrees difference it seems like. I haven't looked at the routing of the air ducts yet, but I know the climate filter is on the passenger side (glove compartment). Is all the warmer air going to that side first?

 

ALL of the system airflow, fresh and recirc, comes through the filter behind the glove box, through the centrifucal blower and then ALL of it flows through the cooling evaporator and is cooled to about 35F, if the system has reached stability (passenger cabin within a degree or so of setpoint).

The airflow is then split four ways, left and right, and two separate mixing vanes control how much each airstream is reheated by passing through the heater core before exiting the vents.

The reheat level, on the average, overall cabin temperature, (sensor above drivers right knee) is determined by the average of the two settings. There are also TWO solar sensors, one on each side of the car just at the bottom inside of the windshield. These sensors will have a very strong influence on the outflow temperature. If the sensors detect that the inclination of the sun is mostly influencing the passenger side then that side will most deffinitely get more cooling.

If the problem persists have your dealer check for unbalanced solar sensors, swap them left to right, or replace them altogether. I suspect that they should be repalce as a matched, or balanced set.

 

Its like what wwest said about the sun, have the dealership put 2 thermometer's, one in each vent. Take a reading with your car, then have them test a new car, see if there's a big difference. If there is have them change the sensors out...

Aloha