CLUM

With AC set to off and the temp set to low and vent on fresh air (not recirculated), the air i get is usually warm instead of cool. For example, on a 60 degree day in SoCal, the air coming through the vents would feel 70ish degrees. I would roll the windows down and get much cooler air. It's almost like the heater core is still open, making my air warm. Anyone else have this problem?

Update 2/20/18:

Brought the car in to my local Lexus dealer and explained the issue to them. They seemed reluctant at first, having a hard time believing the issue, saying they've only had to replace Servo motors on A/C-On related temp issues, not A/C-Off. 3 guys that I talked to all said the air "felt normal"....but I knew it was not normal...hasn't been since day 1 and I'm going on 3 years now). After a back and forth with various employees trying to convince them that's it's a real issue, the Service Advisor/Manager guy got his Tech to plug in their Snap-On diagnostic computer and they found 3 stored diagnostic codes. I had no idea the computer even stores these codes (separate from CELs), so that was interesting.

B1453: Air Outlet Damper Cool Control Servo Motor Circut (Driver Side)
B1454: Air Outlet Damper Cool Control Servo Motor Circut (Passenger Side)
B1455: Air Outlet Damper FOOT/DEF Control Servo Motor Circuit (Driver Side)

Once they found the codes, they backed down and immediately informed me that they would replace the servo motors and I should get the car back within the next couple days.

I'm just glad they found stored codes because I wasn't getting anywhere simply explaining my issue. If there weren't any codes, i have a feeling they would have turned me away. They gave me a ES loaner car and the air feels normal in it, so I know i'm not crazy (and i knew i wasn't crazy once other CL members here stated they had the same issue). Hopefully i'll report back with good news in a few days when i get the car back.

mopudding

I have the exact same issue with my 2014. I've found hitting the A/C for 10-15 seconds, then going back to regular air causes it to pump cool air from outside. It's as if the system doesn't change air from engine to outside properly.

skiracer

I do the same...

CLUM

hm interesting fix. Thanks for the info. i'll try it to see if it works for me too.

DJSpeed

well from what I learned is that the ac unit uses the outside temp to correctly set the inside air temp.....

example is that if the outside temp is 70 degrees.. and the temp on the head unit is set to 80 it will heat the inside
if you set it to 70 it will blow only air or if you have it set to auto it will bring the fan speed slower
and if you set it to 65 for example then it will cool inside the car.

so with knowing all that... if its 60 degrees outside I think the lowest setting on our cars is 60? before it says low.. so the main thing that we don't know is what is the threshold cutoff for the LOW setting.
if our outside temp shows lets say 58 and we put it to LOW how cold will it still get with a LOW setting? whats the difference in temps before the heater core closes and strictly runs on the air compressor?

my theory is that anything 65 or below is considered cold by lexus standards so the system keeps the heater core open for standby heat. since the system relys on the outside temp monitor of the car to figure out how to correctly adjust the amount of hot water goinf thru the heater core

CLUM

To me it just sounds like the heater core is left partially open, either by mechanical problem or software issue, which turning on the A/C fixes by closing the core completely.

DJSpeed

funny u say that.. to test the theory. I just got back from the store and it is exactly similar to ur situation its 59 outside right now. and when I open circulation it was slightly warm air.. so what I did when I got home. I then poured warm water over the front bumper area where the outside temp sensor is. it brought the outside temp sensor on my car from 59 to 73. went for a drive again and put some gas in the car. this 2nd time around the open recirculation was blowing almost same temp air as outside. not warm like last time.

this just may be my car or a fluke but I still think it adjusts the amount the valve opens for the heater core based on the outside temp

CLUM

That's interesting...If that's the case, the ECU's logic doesn't make sense then and there must be a bug. Let's say at 59 outside, your car was giving you 65 degree air inside. Then you put hot water on your temp sensor and your car read 73, so now you say it's giving you 59 degree air (same as outside air)? I can't find any logic behind that, so i'm inclined to say it's a fault with the car from the factory then...

If the car is capable of giving you 59 degree air, then it should do it whether the temp sensor shows 59 or 73 ambient temp (IMO at least). The way automotive climate control usually works is that full cold on the adjustment = heater core closed completely, therefore, vent air is 100% whatever outside ambient temp is. If it's 10 deg outside, then you get 10 deg air inside. The moment the temp control is raised and the occupants want warmer air, the heater core opens and allows hot coolant to warm the core and ambient air is warmed up as it passes over/through the core.

The way i'd want to test it is to put temp on LOW and physically check if the heater core is completely closed at the hose valve. Then check again with the A/C on and see if there's in fact a difference (ie. if the hose valve is more closed with the A/C on).

Drawblood

I know a ton of people have had issues with the plenum doors getting stuck on the 2014/15 models. It requires a full replacement of the door and servo assembly. I hope this helps...

DJSpeed

I' just thinkg more like this. If the car knows it' cold outside it' going to leave ur heater core open (for whatever Lexus programmed it). But let' say lexus programmed the heater core to read the outside temp and to have heater core 100% open below 60 outside. Then 50% when its hits 65 and 100% closed its 70 or above. That way heat is readily available when u need it.

now I'm just speculating on this because I have a friend with a 2015 who changed out his valve. And it still does the same thing. Maybe they changed the programming on the 2016+

of course I could be completely wrong and none of this is true. Lol. But things like this me and my friends like to toy around with since everything on these cars are computer controlled.

ISFWes

My 2015 IS 250 F Sport was in the shop for this similar reason. The climate control doesn't control very well. It's almost like it has a mind of its own. You can go hot or cold. Dual on or off. And it will normally blow warm air out the front vents. And cold out of the rear seat center console vent.

Lexus reinitialize the system and it went cold and stayed there till you selected hot or turned off the car. Lexus then changed the 2 servo mixing valves with no luck. Then they had some engineers come out and spend two weeks on my car. They ended up changing the two temp doors. And it's working ok.

dojoman

iTrader: (5)

I have the same issue my interior is much warmer than outside.

600rr

I created the same thread a few months ago. Many folks here brushed it off and said I was just complaining.
Like someone said, I just turn the A/C on for a minute and that seems to fix the problem. However, it does get warmer again after a while.

CLUM

Thank you both for your responses. It's good to know that this is a real issue and not made up in my head! Could i ask a favor? i want to know the part numbers that were replaced. Any chance to reference your service orders? I'd like to know the exact parts replaced, since only one of you referenced a servo assembly.

ISFWes

Here is my invoice.