I have a 2004 RX 330 with 289k.
I have noticed that when I turn the heater on the 2 vents facing the passenger seat continue to blow ice cold air. The 2 events facing the driver blow very hot air.
120° from the 2 drivers vents, and 56° from the passenger events. (it doesnt matter if the AC is on or off)
I already understand how the "dual" setting works and how each side can have a different temperature. I set the level to the highest heat on both sides and it doesn't matter if Dual is on or not, it continues to always blow cold air through the passenger vents. I don't have to worry about this during the summer months, but now that winter is approaching I have no hot air to come out of the 2 events facing the passenger.
Has anyone ever seen this happen before? I have tried everything including the recirculate button, ac on or off, mode set to vent or floor. still always cold coming out in the direction of the passenger.
HELP!! my passengers are getting cold.

 

Hi Brucecav, this servo flap controls temp on that side.

Very easy- remove glove box first and then pull a black plastic downward vent tube off and out of the way(vent only held in with 2 claw clips).

Adjusting the temp up and down you will see the white linkage move up and down from this servo.
What you are seeing here is the all the way down position for max cold/no warm for the air mix.

I took this pic for another member, plz follow up and let us know how it goes and what you find.

 

Thank you!! Sobi just pull glovebox down, like when I change the in cabin filter ?? Or does it have to be totally removed?
I'll try this weekend. Thank you

 

There are LH and RH blend door actuators that control the amount of heat u get out of each side
the pass side has the correct heat but is cooler on the drivers side
i just today installed a new drivers side actuator $160 Amazon and confirmed that it worked correctly.
with the heat on hi it still isn’t great so I still haven’t quite figured it out.
the heating sys has no coolant control valve so it’s full flow thru the heater core and the heat is controlled by a flapper door restricting the flow of ir through the heater core.
i have also operated the flapper door manually and still couldn’t get max heat but it was better
the new actuator did have the blend door flapper all the way in heat position but heat was still warmer on pass side
if you want to check urs both L&R blend door actuators are easily accessed bottom of centre console
remove plastic covers put seats all the way back ...a cushion across the rocker panel will save ur back cuz u have to lay upside down to see the actuators on each side...a 90deg electric driver with Phillips screwdriver bit will help cuz it is tight in there
there are three screws ...one top and 2 bottom...remove them and the actuator pulls off and will hang from the wiring harness
operate the heat control and watch the actuator operation....with your finger move the white plastic flapper lever back and forth and the heat should go hot and cold respectively and you will see the range of motion required to get the desired temps good luck and let me know how it worked for u....a new actuator is hopefully the fix for u and remember there is a left and a right

 

I see this is your first post, soooooo welcome to club lexus!
This is true what you said, no coolant control valve like on other cars.
What's your theory on this so far?
I'm thinking possible partial restriction of the heater core but only if not using the red Toyota coolant -or- low coolant flow at idle rpms in cold weather might be normal for Canada, just an idea.

 

The bottom of the heater core is visible near the blend door actuator and at 190F is hot to the touch. Get an infrared thermometer and scan the edge of core to know its temp on both sides…not likely it’s a plugged core
remove the blend door actuator on the cool side and operate the flapper door by hand with the engine at operating temp to see if it gets warmer
Note: Toyota heaters are not the warmest at idle and you don’t get the the good heat till you are driving with higher ENG RPM and thus higher flow through the heater core
Thank you for the welcome
We are a Lexus family two ES and an RX

 

Just scanned the heater core inlet and outlet
inlet 200F outlet 170F so it’s plenty hot going in and a 30deg differential we are getting heat
but not great…on vent both outside vents are warmest and inside vents are cooler still trying to see exactly how all the vent doors work together with heater core
ill keep you posted

 

Looking for info on poss thermocouple reset
or is there is a way to know if all the vent doors are working correctly…can’t get it right on manual and the computer controls it when in auto temp/ vent direction. Sooo weird

 

I can't find any reset on the temp sensors.
Just thinking if you already pulled the plastic trim out of the way so you can see full range of motion towards max heat on the air mix servos for both sides you may have the best it can do.
By doing this you already verified it's mechanically switching to max flap opening towards heat.

Maybe can get more airflow & heat replacing the cabin air filter with oem- it looks more "see thru" and higher flow than aftermarket when I was looking at pics.