2001 is200 no heating, thermostat ok

[Lucazade]

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?

[Dean1309]

Hi mate, I would check the obvious first, there is coolant in the expansion tank and radiator, don't forget these cars have two filling points for coolant.

Secondly whats the symptoms the car is experiencing? My old IS200 used to warm up fine at idle, as soon as you start driving, the heat used to go cold and had no heat at all (temp guage went from middle to cold), I suffered throughout the whole winter with no heating. The issue was the thermostat, I had replaced the thermostat when changing the radiator, i replaced the stat with a BluePrint part, the car didn't like it, the thermostat wasn't closing off properly, so the car never kept its temperature. I replaced the BluePrint part with a genuine Toyota Stat and problem solved, never had any issues since then.

[Lucazade]

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.

[Dean1309]

Have you checked the top and bottom radiator hose, the top hose should be hot and the bottom radiator hose should be cooler as its being cooled by the radiator. If they are exactly like this then there is no issue, if they are both cool, there is a problem and I would say thermostat.

I'm trying to suggest the obvious before changing the heater matrix as this will more than likely be a nightmare to do.

My previous Lexus IS200 had 163,000 on the clock and never needed a heater matrix replaced, cooling issues were else where.

[Lucazade]

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 😞

[Dean1309]

This is sadly pointing towards heater matrix, I've read online that the dash has to come out to get to it and get it out. Although, it can be done by removing the hoses to the heater matrix, joining them together so you don't loose coolant and cutting the pipes of the heater matrix to remove. But how you would get the new one without cutting it I don't know. 

https://www.lexusownersclub.co.uk/forum/topic/64252-how-to-change-your-heater-matrix/

[Lucazade]

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?

[Dean1309]

If the water pipes coming from the heater matrix is hot by the firewall that would indicate that water is flowing through, you could also check the heater matrix itself or near the area inside the car to feel any heat around the heater matrix. 

 

It could indeed be the servo motors. They started to go on my old Lexus, used to click when the engine was turned off as if it couldn't negotiate it's correct position, but worked perfectly when the car was running. Only way to tell is to buy another one and swap them out. They are only about £15 off eBay. Think you gotta take the glove box out to get to it. 

[Farqui]

Don't dismiss the heater matrix being blocked and only allowing fluid to flow through a small portion. As mentioned, I would try to gain access to both sides of the core to ensure it is heated throughout.

 

I have flushed mine several times and several small particles were released and the heater works very well now. My heater worked well before so flushing is a worthwhile activity, especially on older vehicles.

 

The heater servos do seem to be a common fault though, so you're right to consider those too. Can you find any heat with any combo of heat output direction?

 

Does the heater fan work?

 

 

 

 

[Lucazade]

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.

[Lucazade]

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?

[Dean1309]

Hi mate the coolant drain plug is under the plastic under tray. Remove about 10, 10mm bolts holding the under tray on, around the edge of the bumper and a few on the underneath of the tray. Towards the passenger side of the radiator is the white coolant drain plug. Although it might be quicker to get some pliers, undo the clamp holding the lower radiator hose on, and pull off the hose. 

[Dean1309]

As for flushing the heater matrix, remove the hoses to the matrix from the engine bay and attach a hose into a bucket and the other end to a garden hose on low pressure. And then swap the hoses around to reverse flush to make sure everything is clear. Use clear tubing if possible to see the colour difference in water coming out of the matrix. When refilling the matrix pour anti-freeze coolant directly into the heater matrix hoses to ensure coolant gets to the matrix, once full re-attach the coolant hoses the correct way it was removed. 

I'm sure you knew that anyway but just sharing some info. 

[Lucazade]

13 minutes ago, Dean1309 said:

Hi mate the coolant drain plug is under the plastic under tray. Remove about 10, 10mm bolts holding the under tray on, around the edge of the bumper and a few on the underneath of the tray. Towards the passenger side of the radiator is the white coolant drain plug. Although it might be quicker to get some pliers, undo the clamp holding the lower radiator hose on, and pull off the hose. 

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?

[Dean1309]

Oh apologies, I have never had to locate that drain plug. I no longer own an IS200 so I can't help you with that one mate. I'm sure someone on here would be able to help though. 

[Lucazade]

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

[Lucazade]

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)