Poor heating in the NX - Anyone else experience this?

[Thackeray]

If the air coming out of the vents is 34C, pretty soon the air throughout the cabin is likely to be approaching 34C.

If you've got an old-fashioned room thermometer (rather than the gun style one in the picture) you could use it to find out what the temperature is in the middle of the cabin, away from the vents. It would be interesting to know what the cabin temperature actually is after a 15-20 minute drive.

I think the design philosophy of the climate control is to make it as imperceptible as possible, whereas it sounds as if you'd like hot air coming out of the face vents, which is the opposite of what Lexus designers are trying to achieve.

It's like the difference between standing in front of a roaring log fire in a cold drafty castle compared with being in a modern air conditioned room set to keep the air at a steady 22C and whatever a comfortable humidity level is. You can certainly feel the log fire. But you don't really notice the effect of the air conditioned room. Lexus is trying to achieve the air conditioned room effect not the log fire effect.

So it would be really interesting to know what the temperature in the cabin is after a 15-20 minute drive with the climate control set to Auto, 22 or 23C, and with no other buttons pressed after pressing Auto.

I'm guessing from your experiment that the temperature will be around 22C. But there won't be any hot air coming out of the face vents. The hot air will be coming out towards your feet. Instead, there will be cool air coming out of the face vents, as DonC says above, to avoid making the driver drowsy.

 

[Deathstar]

46 minutes ago, Thackeray said:

If the air coming out of the vents is 34C, pretty soon the air throughout the cabin is likely to be approaching 34C.

If you've got an old-fashioned room thermometer (rather than the gun style one in the picture) you could use it to find out what the temperature is in the middle of the cabin, away from the vents. It would be interesting to know what the cabin temperature actually is after a 15-20 minute drive.

I think the design philosophy of the climate control is to make it as imperceptible as possible, whereas it sounds as if you'd like hot air coming out of the face vents, which is the opposite of what Lexus designers are trying to achieve.

It's like the difference between standing in front of a roaring log fire in a cold drafty castle compared with being in a modern air conditioned room set to keep the air at a steady 22C and whatever a comfortable humidity level is. You can certainly feel the log fire. But you don't really notice the effect of the air conditioned room. Lexus is trying to achieve the air conditioned room effect not the log fire effect.

So it would be really interesting to know what the temperature in the cabin is after a 15-20 minute drive with the climate control set to Auto, 22 or 23C, and with no other buttons pressed after pressing Auto.

I'm guessing from your experiment that the temperature will be around 22C. But there won't be any hot air coming out of the face vents. The hot air will be coming out towards your feet. Instead, there will be cool air coming out of the face vents, as DonC says above, to avoid making the driver drowsy.

 

yes, maybe. As I suffer from raynaud's, I usually have the vents pointed at the steering wheel to warm my hands. The heated steering wheel is lovely too. I guess its just a different car, different design. 

[paulrnx]

I’m not sure what you are trying to achieve. How would you know what the temperature of the air coming out of the vents should be at any particular point in time?

[Deathstar]

Just now, paulrnx said:

I’m not sure what you are trying to achieve. How would you know what the temperature of the air coming out of the vents should be at any particular point in time?

Simples. When the car was set to 25^oC, the air didn't feel very warm, certainly not 25^oC. My previous IS at 23^oC would be very warm, whereas the NX was not. 

[paulrnx]

11 minutes ago, Dylanlewis2000 said:

yes, maybe. As I suffer from raynaud's, I usually have the vents pointed at the steering wheel to warm my hands. The heated steering wheel is lovely too. I guess its just a different car, different design. 

It’s just automatic climate control as opposed to a manual  system where you control the heat setting, fan speed and air direction. You could mimic this by manually setting the system. In my experience all automatic climate control systems in cars work the same way in terms of trying to maintain a specific cabin temperature in the most comfortable way.

[paulrnx]

4 minutes ago, Dylanlewis2000 said:

Simples. When the car was set to 25^oC, the air didn't feel very warm, certainly not 25^oC. My previous IS at 23^oC would be very warm, whereas the NX was not. 

But you aren’t setting the temperature of the air coming out of the vents, you are setting the temperature you want the cabin to be. The temperature of the air coming out of the vents will be dependent upon how cold or warm the cabin is at the time.

[Deathstar]

12 minutes ago, paulrnx said:

But you aren’t setting the temperature of the air coming out of the vents, you are setting the temperature you want the cabin to be. The temperature of the air coming out of the vents will be dependent upon how cold or warm the cabin is at the time.

Yes, however, when I'm cold in the car, I would expect setting it to 25, it blows out warm air? Or am I missing a concept here?

[Pielight]

9 minutes ago, Dylanlewis2000 said:

Yes, however, when I'm cold in the car, I would expect setting it to 25, it blows out warm air? Or am I missing a concept here?

I would not take much notice of the number…23c may feel like toast in one car but quite cool In another (depending on location of sensors in relation to heat outlets etc etc). If it’s not as warm as expected (with engine thoroughly warmed up of course) simply turn it higher. As long as you can get a setting high enough to be warm then that should be fine. Also make sure the vents are open and directed as appropriate and that the CC is set to auto.

[Thackeray]

2 hours ago, Dylanlewis2000 said:

Yes, however, when I'm cold in the car, I would expect setting it to 25, it blows out warm air? Or am I missing a concept here?

That's not quite how it works. If you have the climate control on Auto the answer depends on what the current cabin temperature is. For example, if the cabin temperature is 20 and I turn up the temperature setting from 20 to 25 I would not expect to get warm air out of the face vents because the required rise in temperature is only five degrees. I'd expect cool air to continue to blow from the face vents and warm air from the foot vents until the cabin temperature reached 25. But I wouldn't expect warm air from the face vents at all in this example.

But if the car had been standing overnight, the cabin temperature was zero and I set the cabin temperature setting to 25, I'd expect no air from the face vents until the engine had warmed a little. Then there would be luke warm air from the vents and much warmer air from the foot vents. This is for two reasons. First, the heating has to raise the cabin temperature 25 degrees so it will need to pump out quite a lot of hot air from the foot vents to achieve this. And second, the only source of cool air initially is from outside, where the zero degree temperature would provide uncomfortably cold air to the face vents. So until the cabin temperature has risen a bit, the face vents will have luke warm air that is a little more comfortable than freezing cold air from outside. When the cabin is warm enough the air from the face vents will be cooler than at first.

Paul has pointed out above that you aren't setting the temperature of the air coming out of the vents. Instead, you're setting the temperature you want the cabin to be. I had forgotten until now that before climate control was common in cars you would set the temperature of the air in a range from cold to very hot. When you started off in the car in winter, you would set maximum temperature, maximum fan speed and demist vents. As the car warmed up you would then reduce the air temperature, redirect the air to the floor vents and reduce the fan speed; and so on as the car warmed up. I'd forgotten this was normal routine!

But you may be able to emulate this by not using the Auto settings. Sorry to hear of your Raynaud's; maybe the heated steering wheel will help as well - I've never tried one. But if you want warm air from the face vents you may be able to achieve this with manual settings. What I'm not sure about is whether the temperature of the air from the face vents will still go down as the cabin warms up, even if you have the setting on High. Perhaps it won't and you'll be able to achieve what you need for comfort. Let us know how you get on after some experimentation.

[Thackeray]

When I went out in the car today, I thought I'd better check if I was right in what I said above. It turns out there's a bit more subtlety to the climate control than I thought.

The outside temperature was 5C when I turned on the car and presumably the same inside the car. The engine was cold and the climate control was set to Auto and 21C. I was surprised to find that air comes out of the windscreen demist vents right from the start. I didn't know that before. But of course the air was cold initially while the engine was cold. I didn't realise there was always air from the windsceen vents right from the start, not just when you select Demist.

After two minutes the air from the windscreen vent began to warm up a little but there was no air coming from other vents. Then five minutes after starting I heard a flap open and warm air began to come out of the footwell vent. But there was still no air from the face vents. Then around eight minutes after starting the engine, a trickle of warm air started to come from the face vents.

Then around 10-15 minutes after starting the engine, with the engine temperature gauge approaching normal, the fans started to speed up and more warm air came from the face vents (and the other vents, of course). This presumably speeded up the process of getting the cabin up to the set temperature.

What surprised me, though, was that after 30 minutes from starting, although the fans were slowing down a bit, the air from the face vents was still warm (though not hot). I had expected there would be cool air by now. I found that if I reduced the set temperature to 18, the face vents produced cool air instead of warm. I assume this showed that the cabin had reached 18 rather than 21. With milder weather than today, the face vents would produce cool air sooner than when the outside temperatures were fairly low like today.

 

 

[NemesisUK]

I suspect a lot of what you observed is to do with physics, warm air rises, cool air falls?

In really warm weather, ice cold air come from the face level vents to fall and cool the cabin, it's effective as passengers feel this cold air. This operation though is detrimental to the operation of the seat ventilators, which draw air from the footwells, which are still relatively warm. To improve this function one would cancel Auto operation and select footwell vents. Cools one seat much more quickly but leaves one's face and upper body feeling warm.

In really cold weather warm air is pumped out from the footwell vents to rise and warm the car, slowly effective but leaves passengers experiencing the relatively cold air on exposed faces.

I find the climate control in my RC the most effective I've experienced in any car I've owned. I never leave the car idling to warm up preferring to drive away once I've scrapped clear the windows, only a minute at most. as noted by @Thackeray above air exits the screen vents immediately on starting and forcing screen demist will slowly clear any fogging on the inside of the screen, usually clear by the time to drive away. Really impressive is the rear screen demister, it usually clears the rear screen very quickly, only 3-4 minutes into the drive. After only 5 minutes driving warm air is filling the cabin (I switch the screen demist off as soon as it's cleared) and the fans ramp up. Within 8 minutes the fans are slowing down to normal background speed and the cabin feels comfortable (I set the cabin temperature to 20c). 

The steering wheel heater, is switched off fairly quickly, I don't like a sweaty wheel and the seat heater is on auto, so slowly ramps down as cabin temp increases.

All-in-all very effective and I suspect, in no small way attributable to the neural network climate control, which after reading the Lexus.eu tech doc appears very comprehensive and flexible in it's interpretation of signals from various sensors, ambient, coolant, solar and the desired temperatue.

I think the only omission is recognition of open windows, although it does appear to know when the sunroof is open. Very clever these Japanese! 

[DanD]

I suspect that the RC heats up quicker than the NX due to the different cabin dimensions, and in particular height.

Also, as mentionned before, if you have the pan roof, closing the sunshade will help speed up the warming up of the car by providing a little more insulation.

I think that William @Thackeray's comments are spot on.

The numbers displayed are indicators only and do not reflect an exact temperature setting. 25 does not and cannot mean 25 degrees as the temperature will vary from one part of the car to another.

If you really want warm air to your hands, the only way to go is to manually override the system.