IS250 – climate control not controlling

[LexV84me]

Please advise...

Bought an ‘09 IS250 SE-L (satnav and ML) last week. 

Very happy all-round, but I’m confused by the climate control: when I select Auto and set the temp, instead of maintaining the desired clime it blows like a weapons-grade hairdryer one minute, then changes to an icey blast, then reverts to furnace mode, then cold again – ad nauseam. 

Am I doing something wrong or is there a sensor problem?

Ta 🙂

[Texas]

As a first point, check that the cabin air filter is all good in the rear of the glovebox, 

Note: Make sure ‘Re-Circ’ is on before attempting to open access door to filter or it may get damaged, £££££’s

 

[LexV84me]

On 2/14/2021 at 4:42 PM, Texas said:

As a first point, check that the cabin air filter is all good in the rear of the glovebox, 

Note: Make sure ‘Re-Circ’ is on before attempting to open access door to filter or it may get damaged, £££££’s

 

Thanks for reply. 

I checked the filter, it seems fine: a few bits of loose debris but not caked in years of dust. 

Any other suggestions, please?

Ta 🙂

[Linas.P]

Can you give little bit more detail of settings and conditions e.g. outside temp, what temperature you have set, is AC on, fresh air or recirculation? 

It may still be an issue with some sensor as it seems system is certainly not working correctly based on what you are describing.

[LexV84me]

On 2/24/2021 at 3:50 PM, Linas.P said:

Can you give little bit more detail of settings and conditions e.g. outside temp, what temperature you have set, is AC on, fresh air or recirculation? 

It may still be an issue with some sensor as it seems system is certainly not working correctly based on what you are describing.

The ambient / exterior temps over the past few weeks I've driven the car have ranged from -2°C to 14°C.

The button on the far left is set to Auto; the right button(s) is set for fresh air. Fan off.

Whatever level I select the temp - eg, 24 during the recent cold snap - it oscillated between too hot and too cold. If I tried re-setting to 22, same result.

Over the last few days the ambient has been c.14°C, so I tried setting to 20, but after a while it becomes too hot, then too cold. 

And I've noticed that the two vents above the centre console emit different temps: cold from the left, warm from the right. Huh?

Your thoughts?

Ta 🙂 

[NemesisUK]

Why the fan off? How do you imagine the system can move the air around?

Set everything to Auto and the temp to what you want and let the car control the air distribution.

[LexV84me]

37 minutes ago, NemesisUK said:

Why the fan off? How do you imagine the system can move the air around?

...

Because every car I've driven with digital climate control - which includes Seats, Porsches, Ferraris, JLRs, Maseratis, Astons, and a Mercedes delivery van - to set a constant in-car temp irrespective of ambient temp, the process is the same: select Auto, select desired temp, let the system control the in-car temp. For example, enter the car during a 30°C ambient summer day, select Auto, set the temp to 20, and initially the fan will blow like a tornado, then gradually diminish to almost now't as it lowers the in-car temp to 20.

Is a Lexus / Toyota system different? 

Ta 🙂

[Linas.P]

So fan not off... it is basically on auto. Because if you change fan settings I believe it automatically disables auto. In short I think you right - climate on Lexus works like any other cars. Set it to auto and it will determine what fan speed needs to be. 

AC on? and Dual off?

[LexV84me]

1 hour ago, Linas.P said:

So fan not off... it is basically on auto. Because if you change fan settings I believe it automatically disables auto. In short I think you right - climate on Lexus works like any other cars. Set it to auto and it will determine what fan speed needs to be. 

AC on? and Dual off?

Correct, fan-on cancels Auto.
Yes, AC on and Dual off. And I’ve tried with Dual on – same result. 

[Linas.P]

Yes... nothing wrong with your settings.

Really bizarre why it does that. 

[ColinBarber]

Seems like you have a sensor or servo issue. Diagnostic equipment would be needed to see what is happening at the point when it changes from hot to cold and understand why the passenger output is different from the drivers.

[NemesisUK]

16 hours ago, LexV84me said:

Because every car I've driven with digital climate control - which includes Seats, Porsches, Ferraris, JLRs, Maseratis, Astons, and a Mercedes delivery van - to set a constant in-car temp irrespective of ambient temp, the process is the same: select Auto, select desired temp, let the system control the in-car temp. For example, enter the car during a 30°C ambient summer day, select Auto, set the temp to 20, and initially the fan will blow like a tornado, then gradually diminish to almost now't as it lowers the in-car temp to 20.

Is a Lexus / Toyota system different? 

Ta 🙂

In my RC there is Fan Off which disables the climate control and then there is Fan Increase and Fan Decrease. The latter two buttons customise the fan speed but do not change the Auto settings for distribution.

Your description of operation is as I would expect. It's just when you mentioned 'fan off' I thought your IS system was as my RC.

Definitely sounds as though your controller is confused. As Colin posts above, diagnostics required to see whats going on! 

[Brechin Slate]

On 2/14/2021 at 4:42 PM, Texas said:

As a first point, check that the cabin air filter is all good in the rear of the glovebox, 

Note: Make sure ‘Re-Circ’ is on before attempting to open access door to filter or it may get damaged, £££££’s

 

Does anyone know what physically happens to prevent the filter removal if not in recirc mode?  Which bit actually breaks? Just curious.

[Texas]

The servo arm that moves the door/flap gets broken I think if you try and open it manually and not available as a spare part and whole unit has to come out ( Somehow?) very expensive  and needless repair if instructions on filter replacement are followed exactly!

[Brechin Slate]

1 hour ago, Texas said:

The servo arm that moves the door/flap gets broken I think

Ah, thanks Texas.  Had a look at my filter yesterday following the correct procedure just to check the condition.  Couldn't see anything that would snag, catch or obstruct the filter, probably because I did it properly though!

[Texas]

With the access panel at the back of the glovebox removed then if you toggle re-circ button on & off then filter door/flap should move if all is ok.

[LexV84me]

After consulting some franchised Lexus garages - cue much sucking of teeth and strategically vague estimates of job-length / cost, etc - I tried the garage (indie) that looked after my various VAGs over the years.

"Do you know when it last had a re-gas?"

"Umm, no, the car's new to me."

"Bring it in and we'll check the Freon level."

So, long story short: the Freon level was 90 - it should be 440.

After a re-gas, all is well; although the interior temp-setting needs tweaking when the outside / ambient temp changes.

PS Can anyone recommend an honest and fair Lexus / Toyota indie garage in London, please? (Spark plug service due soon-ish.)

[Mr Vlad]

Did your guy check where the leak was with your car having such a low freon level?

[Texas]

It does leak out slowly in time so without knowing when it was last re-gassed then it might have a leak that warrants investigating or it might just need it periodic top-up.

If it has got full LSH then you can check if it has been gassed in the past on ‘Lexus Link’