Lexs400

here's the scenario,
the defog mode isn't defogging the whole window, half of the fog stays, yet the air from the defog mode vents is coming out.
when set at auto, even at 75F, the heat from the foot well is way too hot for that temp.
the fan setting seems to be operating normally in auto mode.
Is there an ecu or another device that controls the proper operation of the climate control ?
this one's with Nav, don't know if that makes a diff.
any comments would be appreciated.
thnx.

Lexs400

I had the lx compared to my friend's lx today.
seems like the intensity of heat from the lower vents with the heater on is almost twice as much.
I would like to know which part could be faulty to produce this situation.
The dealer had the error codes checked and didn't find any error codes.
and as always, the tech at the dealership has no clue on how to troubleshoot at the dealership.
any ideas would be appreciated.
thnx

VVT-i

Do you have any steering column work done lately? There is a little sensor right below your ignition key. If you look down from the igintion key. You will see a small vent, but you have to remove the lower dash cover and make sure that sensor is plugged in properly.

Lexs400

the dealer had to replace the steering column motor.
now there is a rubbing noise when the steering is moved, but yes to answer to that question it was done.
the truck is at the dealer and the service advisor did mention the sensor and told me that they checked that already.
somehow I don't believe it.
at the same time, after the work was done, i smelled the burn of electrical components coming from under the dash on the driver side. Give everything seems to work, I'm not sure what part was fried...
would a bad sensor give an error code. more over, if there is an error code in the climate control where would those codes be stored and where do i plug in the obd to check

VVT-i

You may need to go to the dealer and talk to the D.S ( diaganostic specialist) and give him all the details and conditions. I mean, the outside temp, the setting temp. and show him about the problem. Each Lexus dealership will have at least one or two D.S.

Lexs400

i drove my friend's lx tonight for comparison sake.
the problem is not related to outside temp. or inside temp.
it is the intensity of the heat that comes out of the lower vents, that's the problem.
it's almost as if the cool air is not properly being mixed to the hot air before it gets sent to the vents for inner circulation.
if that makes any sense...
other than that the climate control is working how it's supposed to. it switches from hot mode to cold mode, different vent settings etc etc.

Lexs400

well the dealer called. said couldnt find anything wrong with it so i picked it up and drove home. on the way back the weather was better than usuall so I turned the heat down a bit to get some fresh air. down to 70, then 68, then 65... but the center dash vents kept blowing luke warm air and the side vents were throwing colder air. that's just not right.
the center vents should only be throwing out cold fresh air when the temp is down to 65.. anyhow i then put the temp control to 'max cold' and all of a sudden i heard some vents pop open and in came the gush of fresh air...
my question now is... what could be causing this issue..
is it the climate control ecu, or some other ecu.../ part.. ?

Jet

check the cabin air temp. sensor thats located under the ignition switch. 95 percent of the HVAC problem i came across with similar concern as your is that sensor, being either unplugged or the hose not connected to it. if its connected properly, take the sensor out and make sure you dont have debrie covering the sensor tip.

Jet

VVT-i

You may have the problem with one of the vent door that direct the air into difference mode. If one of the door got stuck it will not direct the air to the vent properly. These vent doors located behind the dash, you can check by select the air outlet mode and make sure each mode is work correctly.

Lexs400

vvt-i,
thanks for the input. i will look into that as well. however would you be kind enough to elaborate on the process for checking the vents.
i am assuming that by air outlet mode you mean switch from bottom vents to front vents etc.
those seem to be operational to the point that if when the front vents are selected they start throwing air. however the air is not "fresh" the only time i get the cold fresh air inside the cabin is when i drop the temp down to "max cold" setting. anything other than that settings gives luke warm air from the center and side vents...

Lexs400

allright, as for temprature irregularity and jumpiness, here's what I have found out.
the inside temprature sensor is located right under the steering column below the key area.
it has a plastic pipe going to it that starts from the driver's side footwell.. However the end of the pipe at the footwell isnt really hooked up to anything. atleast it wasn't in mine. it's just sitting there hoping to suck some air in and travel to the sensor. otherwise the sensor is only getting the input from the tiny opening on the under dash panel.
I took the sensor out from it's locaton and moved it under the footwell next to the heat outlet for the footwell.
and it's a day and night difference. the climate control is actually behaving itself. where setting the temp around 75 actually does regulate how it should. it's not jumpy and pushing the auto setting to 75 deosnt create a baking oven environment inside.
so if anyone wants to just try to find the optimal location for the insided temprature resistor they can. to check whether or not that sensor is working, unplug the wire from the sensor and you'll see an immediate increase in the blast of air that comes through from the vents. Clean the sensor while you're at it. it just looks like a very small resistor. two wires and then a round brown colored piece attached between the wires.
now the only thing left to troubleshoot is the intensity of heat that gets thrown out when the heat mode is on.
I have searched extensively on the heater valve which, when fails, does not allow enough heat inside the car. however I'm not sure if a faulty valve can equate to throwing too much heat inside the cabin....
I would like to get some input from other members regarding this one....