Lucazade

Glad it worked out without removing the dashboard. Replacing the heather matrix could have been expensive, even using a non-OEM part, because of labour. These issues highlight the importance of changing coolant regularly, which I hope they did when they flushed the matrix.

Talking from experience (other car being an E46, which is comparable), an IS is a good financial investment in comparison. The BMW has its qualities - better in some aspects - but maintenance costs are way higher.

Good luck. I'm be interested to know what it turns up to be

If the pollen filter was clogged, airflow would be reduced for cold air too.

Just to clarify from my end - the issue was temperature, not airflow

Changed annually - at least in my case, don't know the other people in the thread

I have now sold my car, but lately described the issue to a mechanic who thought it would be a case of blocked heater matrix. Garages might think it's fine because both inlet and outlet pipes are hot, but what in reality is happening is that some units can have the water going directly from one pipe to the other (this is not a IS200/300 heather matrix, BTW): The solution is to flush it with a cleaner, but that may or may not work depending on the blockage. If it doesn't I'm afraid it's a dashboard out job to replace it

I barely get any heat from the airconditioning. I have changed the coolant (it was clean) Checked the heather matrix, both from the firewall and in the footwell - it gets hot Checked the flaps’ motors (they all work) Checked the air mix flap itself (it moves) Checked the air temperature sensor under the steering wheel (it works) Yet when I put the heating on, even at max temp I only get some mildly warm air, whether the aircon is on or off. Has anybody got the AC unit apart to show me how it works or has any idea what else I could look at? Thanks

After fixing the headlights problem caused by the anti-theft ECU (see separate thread), I got a similar issue again (after pulling the key off, the headlights turned on again and wouldn't turn off, even with the car locked). I started pulling fuses from the main box in the engine bay and the 20A one for the ECU was the culprit. How feasible (i.e. economical) is it to replace it? I can see them on eBay for anything from £20 up. Would it need coding or (assuming I find the exact same part) is it a straight swap? Thanks

BINGO! That's the "theft warning" ECU, for those wondering what the problem is. Anybody still struggling with the headlights issue, now you know what to look for. Still not sure of the connection with having the screen replaced, though ...

Fail. Lights just turned back on. It might be a coincidence, but that happened soon after locking the car so the anti-theft might indeed be the cause.

I think I might have found the issue for my car. Typical symptoms, i.e. lights turning on when pulling the keys regardless of the stalk's position, battery draining overnight, etc. Everything started after having the screen replaced, as usual. I had the bypass wiring fix done by a car electrician so I lost the automatic lights but was able to go through the MOT. However the problem reappeared roughly a year later. This time I had to pull the relay to avoid draining, but then one day I came home with the rear lights on (feebly) and the horn's relay clicking away. Odd. I thought it could have been the anti-theft unit but that uses a separate horn/siren IIRC. Anyway, this time I decided to check the windscreens even if there's no trace of condensation in the fuseboxes, inside or outside. I then checked the windscreen defroster (the wiring that stops the wipers from sticking to the windscreen) and although the wires seems ok, the socket was wet and had a little oxidation. I blew the water off, sprayed some WD40, dried it and left it unplugged but wrapped with a rubber glove's (middle) finger to make it waterproof. No problems so far regardless of the torrential rain we've had overnight. See pics for the area involved, as well as the plug after cleaning it. One thing I noticed is that the cowls' draining slits in that corner don't have a mesh like the others, but I don't know whether it's intentional. I'll keep you posted.

AS we've had a dry Sunday today, I managed to flush the system: not much dirt, but it seems it was enough to slow down the flow in the matrix. I now have hot air too. Curious fact: emptying the system from the radiator only (i.e. without undoing the engine block tap I mentioned previously) resulted in approx. 4.5lt of coolant mix. Considering a dry fill is 7.1lt, it means a fair amount of old coolant/antifreeze has remained inside. Worryingly, it means filling with a 50% mix would results in a diluted mix, since I flushed the system with a cleaner mixed with water (empty system, fill with water and the 250ml of cleaner, empty again and fill with antifreeze mix). (litters - LOL)

I think I've found it via this pic on eBay. How to get to it, however, is another matter ...

I think you're referring to the radiator plug: if so, I got that one already. It's the engine drain plug that I'm struggling to find, as in the diagram it seems behind the inlet manifold. Is that accessible from underneath after removing the plastic shields?

I have checked the servos and they seem to work fine, moving as I changed the temperature and/or air distribution. So I think it's safe to exclude them as the culprit. As there was a bit of dry weather yesterday afternoon, I looked into changing the coolant but I cannot find the engine drain plug: has anybody got a pic or know how to reach it?

Blower fan works fine. There's no heat with either AC on or off. I was thinking to do a flush, as I need to change the coolant anyway. I might do the matrix separately. Thanks for the inputs, guys: I'll check the servos at the weekend and tool up for a coolant change as well, weather permitting.

I wonder whether it's the heater matrix, to be honest. I've just checked the pipes going into the firewall and one was hot and the other just a tad less hot. Doesn't it indicate the water is flowing through? Could there be another reason there's no heating, maybe a faulty servo, such as the airmix motor 87106H (or 87106J for "mode") in this diagram?

Any help is appreciated. I've just checked the radiator hoses and they are exactly as you suggested - i.e. top one hotter than bottom one. As it's a sunny day, the commute home wasn't a problem but I dread tomorrow morning (it's forecast to be 3-4C at he time I'll be leaving home). My car has 153k miles and I really want to keep it, but I already have to get the rear jacking points sorted for the MOT, and if the heather matrix is such a big job, I'll have to consider other options 😞

Thanks for the reply. Both radiator and expansion tank (behind the rad) are full. I didn't know there are two filling points, but that's good to know as I plan to replace the coolant mix soon. The car has no heating whatsoever, from the moment it starts until it stops, after 1h drive in a mix of A and city roads. Some heat seeps through from the exhaust, but that's minimal. The aircon keeps blowing to try to reach the temperature I set (anything up to 28C), with no luck. Turning the AC off does not make a difference. I assume the thermostat is working as the car doesn't overheat and warms up relatively quick, as it used to. The issue started last Sunday, during a 100 miles trip.

The other day the heating stopped working: aircon fine, but now it's getting cold it's a pain to demist the windscreen. The thermostat seems fine as the coolant gauge shows engine temperature to go up as usual and stays in the middle. Does anybody know if this could be the heather matrix (as someone as suggested in the past) and how difficult it is to diagnose/fix?

You might have better luck asking in the is220 forum

This one? https://lexus.7zap.com/en/eu/lexus+is/242210/gxe10r-aefvkw/3/5102/510749c/#52271D

Herbie, many thanks for pointing it out: I completely missed the link button and assumed it would become an active link automatically - my fault. However I'm a bit surprised that you'd need to sign up, as I made the link public. I'll double check next time I do it.

That's a generic pic, as per description: " Using the jacking locations as specified in your car's handbook [...]" There's no Haynes manual for the IS200, AFAIK but happy to be corrected as I searched for a while. However there's this Lexus document which is a bit clearer. 008 lift and support locations.pdf