Heating Problem

Dimmer · April 16, 2014

Hi Everyone. Hope you can help.

My Sc continually feeds hot air regardless of the temp I set the controls at. It's almost as though the system thinks the car is very cold and requires heating all the time. I also don't seem to get any air to the windscreen even on a demist setting.

I am hoping the system is computerised and simply needs a re-boot. Is this the case? or am I looking at new parts.

One or two bars of the LCD display are missing in the segment which shows external temperature. Is this a clue?

Any help or ideas are greatly appreciated. A trip to the dealer looks inevitable at this point.

Look forward to hearing from you.

Paul.

Paul_G · April 16, 2014

I have just had a very similar problem, and as the car was in for the recall, I asked them to look at it. They disconnected the Battery for the recall, and when they reconnected to investigate the heater problem it had gone, along with a TPMS warning also. So I'd definitely try Battery disconnection for a while, I think it's 40 mins to 'forget' everything.

Dimmer · April 16, 2014

Hi Paul.

Thanks for this. Unfortunately the Battery has been off conditioning for a few days, ready for a summer of fun, so this isn't the fix I was looking for.

Thanks again.

Paul.

Harry eves · November 12, 2019

I have an sc430 and cannot get any demist air to the drivers side of the screen despite it blasting out of the passenger side beautifully. Lexus tell me this is a problem with all sc430 ? and has nothing to do with the work recently done by them during recall for passenger air bag replacement! Any help or similar experience and what to do about it greatly appreciated. Harry

OldTrout · November 12, 2019

Harry,

Was it demising OK before the recall work?

John

Harry eves · November 12, 2019

Hi John, yes but it was always a little better on passenger side but nowhere near a different as now. Lexus Bristol where the recall was handled are trying to tell me all sc430 are like this but I cant believe this. Maybe Lexus head office should provide clarity on this. Be interested to know if any other sc430 owners have ever had this problem. Harry

OldTrout · November 12, 2019

Harry

That does rather suggest that they disturbed something. No demist is very inconvenient even dangerous especially on the drivers side.

Other SC430 owners?

John

Neil E · November 12, 2019

6 hours ago, Harry eves said:

I have an sc430 and cannot get any demist air to the drivers side of the screen despite it blasting out of the passenger side beautifully. Lexus tell me this is a problem with all sc430 ? and has nothing to do with the work recently done by them during recall for passenger air bag replacement! Any help or similar experience and what to do about it greatly appreciated. Harry

If Lexus Bristol said that to me, I would ask them if they are prepared to put it in writing so that I could publish it on my you-tube channel.

The offside of the front screen demists just fine and I'm quite certain Lexus designed them all to clear both sides of the screen. If it worked before it went in for the recall it needs to go back to the dealer to be fixed.

Paul_G · November 13, 2019

Mine never did that, I did lose effectiveness, but that ended up being a pressure problem on the whole cooling system, which was easily fixed. I think they're telling porkie pies.

Harry eves · November 13, 2019

It was working fine before the recall work. Lexus Bristol trying to tell me it's a Common sc430 condition! Saying 3 others they have had in all have same dysfunctional delisting as if that's to be expected in this model! Deny it's anything they did during the recall. Tried disconnecting Battery for an hour with no joy. If they cannot come up with a solution I shall be in contact with Lexus head office. Nobody else so far reports similar problem. Thanks for all your help and advice. Harry

Neil E · November 13, 2019

Well if it's a common problem with SC430 models I haven't heard of it and I'm in touch with quite a few owners. Clublexus would usually have a thread or two if it was a known issue but searching for similar faults doesn't seem to reveal anything common and I can't find a clear diagram that shows how the control to the screen vents is connected.

Mine goes in tomorrow for the air bag recall. If I'm able to speak to the technician as I was last time, I will ask if he thinks it's necessary to disconnect the ducts or if it's possible to accidentally disturb the damper control in the process.

If Lexus Gatwick get mine wrong I may have to get the spanners out and do a new tutorial 🤣 I haven't needed to get to the passenger airbag so far but I am concerned that they need the car for 2 days.

Harry eves · November 14, 2019

Hi Neil

Thanks for that. Will be interested to hear what your mechanic says about this. It can't surely be a common problem that has no solution as it is dangerous to drive car unless one has drivers window open to clear screen! Bloody cold in winter. I will wait for your future comments and your mechanics opinion. Harry

Neil E · November 14, 2019

Hi Harry I wasn't able to talk to the tech, I might be able to when I pick the car up next week but I know from my experience of the SC430 that it is designed to clear all of the front screen and it does just that.

Despite having a build thread of 46 pages, I haven't needed to access the heater so have no experience or pictures of the assembly but looking at the diagram below for the lhd model, the driver side damper sub assy and the mode damper sub assy move the 'flaps' that direct the air flow. My suspicion is that in the course of carrying out the air bag recall work something was done accidentally (or not reconnected) to disturb the operation of perhaps the drivers side servo or the duct to the screen on the driver's side.

I've

With the temp set to say 25 both sides. If you try the different modes on the HVAC panel display, can it direct hot air to 'feet only' on both sides and to the centre vents on both sides or is the driver side actually stuck in the one mode?

Harry eves · November 15, 2019

Thanks Neil. I am having Lexus Bristol ask head office about this to get a solution and after a battle they agree they are responsible for putting it right. Will let you know what happens. Harry