[Sharbotcom]

Originally Posted by Breach

I can't make head nor tail of the diagrams on realoem, but the only temperature sensors I can see are located right next to the central vents:

http://realoem.com/bmw/showparts.do?...55&hg=64&fg=40

Breach:

I think they are located in the overhead panel behind the grill (up where the SOS button is). But I'm not 100% sure.

[535MSport]

The intake for the climate control cabin temp sensor has traditionally been mounted RIGHT BEHIND THE CUPHOLDER on an auto so presumably as per E39 if you put a cold drink in the cupholder the car thinks its freezing inside so boils you, if you put a coffee in the cupholder presumably as per the E39 it will think the car is really hot and freeze you to death. Don't have access to ours at the moment to check this but I do know there used to be a small area kind of like a grill with slots in it and the sensor drew air into this vent that had the sensor located behind it.

[HighlandPete]

If I can join in... why do you guys with IHKA 2-Zone Climate Control think there should be 'heat' from the rear face level ventilation grills? You haven't got a heat control adjusting wheel have you? There should be left/right rear air stratification ahead of the ducting to the rear.

Without looking at the F10 schematics, (but from other 2/4-Zone systems) the F10/11 2-Zone is very basic and only has simple face level flows, appears to have no rear tuning. The real car heating runs through the lower footwell ducting.

Whether the front centre face level 'fine adjuster' does very much to the rear flow, I'd be surprised, but certainly don't expect real heat from the face level ventilation, just a stratification from the front settings and how the front of the car is regulated.

If you want to heat the rear, do it with the foot level heating. If there is too much cool air from the face vents, adjust the face ventilation flow rate with the adjuster wheels.

You need 4-Zone to really heat the face level rear vents, as addition PTC heating elements are fitted in the ducting, according to other BMW air flow schematics.

HighlandPete

[Sharbotcom]

Originally Posted by HighlandPete

If I can join in... why do you guys with IHKA 2-Zone Climate Control think there should be 'heat' from the rear face level ventilation grills? You haven't got a heat control adjusting wheel have you? There should be left/right rear air stratification ahead of the ducting to the rear.

Without looking at the F10 schematics, (but from other 2/4-Zone systems) the F10/11 2-Zone is very basic and only has simple face level flows, appears to have no rear tuning. The real car heating runs through the lower footwell ducting.

Whether the front centre face level 'fine adjuster' does very much to the rear flow, I'd be surprised, but certainly don't expect real heat from the face level ventilation, just a stratification from the front settings and how the front of the car is regulated.

If you want to heat the rear, do it with the foot level heating. If there is too much cool air from the face vents, adjust the face ventilation flow rate with the adjuster wheels.

You need 4-Zone to really heat the face level rear vents, as addition PTC heating elements are fitted in the ducting, according to other BMW air flow schematics.

HighlandPete

HighlandPete: I do have heat coming from the back vents. The system works well in my car and as one would expect. As it worked in my previous 335xi. The temperature of the air expressed from the rear vents was in line with the expected temperature to meet the demand of heating/cooling requirements. Cool when cooling and warm when heating. The problem appears to be that this is not the behaviour experienced by all owners of vehicles equiped with a IHKA 2-Zone Climate Control. The 4 zone system allows the back seat passengers to adjust the temperature in a much more controlled fashion. The 2 zone owners still expect to have adaquate heating/cooling mechanism albiet controlled by the front seat passengers. The rear seat passenger should be able to maintain some control of the rear temperature by adjusting the flow of the air (which they do have control over), however in absence of warm air in the first place, it is of no use - in fact in our climate it is down right dangerous. I would also be very upset if I had cold air expelling out of the rear vents when the conditions called for warm air.

Bill

[EV0LVE]

If you dont have a 4 zone climate control, there is no way to get hot air on the rear central vent. Thats just the fact. If anyone with 2 zone climate control got continuos hot air on the back then post what setting you did. If you have 4 zone then dont post that you're getting hot air on the back, of course you are, thats what the 4 zone is for. Its a design flaw.

[HighlandPete]

Originally Posted by Sharbotcom

... The 2 zone owners still expect to have adaquate heating/cooling mechanism albiet controlled by the front seat passengers. The rear seat passenger should be able to maintain some control of the rear temperature by adjusting the flow of the air (which they do have control over), however in absence of warm air in the first place, it is of no use - in fact in our climate it is down right dangerous. I would also be very upset if I had cold air expelling out of the rear vents when the conditions called for warm air.

But isn't the issue with 2-Zone, the driver/passenger settings are dictating the rear air flow temperature. After all, it isn't the heating as such, the foot level ducting will warm the rear, (if set accordingly up front), it is the ventilation that is the issue.

How can that be hot, if the front is warm and the face level ventilation is moderating to a cooler flow. There is no potentiometer (temperature adjuster wheel) in the rear of the 2-Zone, so how can the rear passengers have any influence on the cars temperature in the rear?

It is not like the older systems in the E60/1 and E9* cars, which don't have a 4-Zone option, but do have a rear 'heat adjustable' face ventilation.

Do sense BMW have cut a corner here, (that may be a reason to feel bitter)but do offer the option of a better 4-Zone system. Same for models like the E70 X5.

HighlandPete

[HighlandPete]

Originally Posted by EV0LVE

... If anyone with 2 zone climate control got continuos hot air on the back then post what setting you did.

That is the only way to know what is going on.

Personally I can't see it staying warm/hot as the car warms, when set on full auto, as the air stratification moderates the temperature, even if there is initial warm up. Happens in all IHKA systems.

Some have observed and reported this cooling as the car warms. I'd be personally setting the 'semi' manual functions, trying face level only, and playing with the temperature to see if you can hold the hot flow, but I wager the front will be pretty hot to do so.

HighlandPete

[535MSport]

Ok boys, direct to you from the manual (you know that paper book thing in the glove box)-

Switching the rear automatic climate
control on/off
1. "Settings"
2. "Climate"
3. "Rear climate control"
The rear automatic climate control is not operational
if the automatic climate control is
switched off or if the function for defrosting or
defogging the windows is active.

[Sharbotcom]

Guys:

On my way into the office this morning I monitored the air temperature being expressed through the rear vents (to be clear I'm talkng about the ones housed in back of the centre armrest). The outside temperature was hovering between 0-1C and the interior temperature was set to 20C (on the "all" setting). Throughout the trip (actually I remembered to do this after about 5-10 minutes into my trip) I kept holding my hand in front of the upper side vent, driver's footwell area and in front of the rear vents. In all cases the temperature of the air being expressed by all vents was the same (as accurate as I'm able to judge with my bare hand). The upper centre vents on the dash did vary in temperature based on the position I adjusted the red/blue scroll.

If I had rear seat passengers they would have felt same warm air emitting from centre console vents as I did in the other non-centre vents up front. The only climate control they would have (short from onpening the window) is in the adjustment of the volume of airflow being expressed by adjusting flap in the the centre vents. Note: 1) I did not attempt to reach under the front passenger seat from the rear to feel the temperature of the air being expressed by the underseat vent; 2) when the temperature of the air dropped coming from the front vents, so did the temperature coming from the rear vents; 3) I have yet to do the same test by turning off "all" and adjusting the passenger temperature to see if the rear temperature is controlled by it (I need a passenger to do the testing As I don't want to be constantly reaching over and feeling the air in the passenger-side footwell while driving ).

I also distinctly remember passengers adjusting the vents to increase cold air flow when the airconditioning was on. My conclusion is while the air source for the centre rear vents may contain some fresh outside air, its path must be routed in such a way as the heating/airconditioning system can influence its temperature.

The behaviour of the rear vents IN MY CAR is exactly the way I expect it to function - it provides some level of climate comfort and control to the rear passengers while leaving them at the mercy of the front seat occupants. The 4 zone system puts the control of the climate and comfort of the rear passengers into the hands of the rear passengers and is a much more effective system.

Bill

[HighlandPete]

Originally Posted by ToddR

Ok boys, direct to you from the manual (you know that paper book thing in the glove box)-

Switching the rear automatic climate
control on/off
1. "Settings"
2. "Climate"
3. "Rear climate control"
The rear automatic climate control is not operational
if the automatic climate control is
switched off or if the function for defrosting or
defogging the windows is active.

But aren't you talking of the 4-Zone, when speaaking of "rear climate control"?

HighlandPete

[HighlandPete]

Originally Posted by Sharbotcom

.... In all cases the temperature of the air being expressed by all vents was the same (as accurate as I'm able to judge with my bare hand). The upper centre vents on the dash did vary in temperature based on the position I adjusted the red/blue scroll.

.... 2) when the temperature of the air dropped coming from the front vents, so did the temperature coming from the rear vents;

My conclusion is while the air source for the centre rear vents may contain some fresh outside air, its path must be routed in such a way as the heating/airconditioning system can influence its temperature.

The behaviour of the rear vents IN MY CAR is exactly the way I expect it to function - it provides some level of climate comfort and control to the rear passengers while leaving them at the mercy of the front seat occupants.

Bill

Excellent experiment.

That is exactly as I'd expect it to run, if I was in the 2-Zone system.

The air is blended, (there is a flap control), before it is ducted to the rear. But as you say, at the mercy of the front users.

HighlandPete

[Sharbotcom]

So, for those who have the 2 zone system and apparently only get cold/cool air out of the rear vents housed in the centre console, try the experiment as described above (alternating your hand between the under dash vent in the drivers footwell and the rear centre console vents). The best measure would be done once the car engine has already warmed up and the centre dash vents (the ones controlled with the red/blue setting) is either set to be midway between red and blue or turned off completely. Force the system into a warming cycle by turning the heat up few degrees. If the expelled air in the rear continues to be cooler that the air expelled under the dash, then I would say you have problem. If it is the same then I'd say it is working as intended.

Bill

[islandnipper]

Originally Posted by HighlandPete

But aren't you talking of the 4-Zone, when speaaking of "rear climate control"?

HighlandPete

That's certainly how I've read it (I've got the 4 zone control).

[lodewijkV]

So, I did read this whole tread and I thought: it's time for a "heat-test-trip"!

I just went out for a drive in my F11, it has got the 2-zone climate control whit the 2x auto buttons.
The settings: Outside temp (8°C), inside temp (22°C), center vent on full red (warm).
My finding:
When the car is heating up there is hot air coming from all vents! Even from the rear center vent.
But after a while when the desired temp is reached the center rear vent starts to blow colder air. Which is actually completely normal in my opinion because the rear foot vents are still blowing hotter air, so the mix makes the perfect temp.
But when you turn up the temp to 28°C (max) the center rear vent starts to blow hot air again.

So my conclusion is that when you have the 2-zone climate control, the car regulates the temp in the rear itself, depending on your settings in the front.
And if you really want to have a different temp in the rear of the car you should take the option of the 4-zone AC, which all makes sense.

[535MSport]

I have always had hot air available from the rear behind the console vents ever since my 1999 E39. The quote I listed above from the manual said nothing about 4 zone so perhaps it is possible to deactivate the rear vents or perhaps some vehicles never had them activated. I haven't had the opportunity to test this theory yet but definitely hot air should come from these vents as well as from those underneath the front seats aimed toward the rear passengers feet.

[HighlandPete]

Originally Posted by ToddR

The quote I listed above from the manual said nothing about 4 zone so perhaps it is possible to deactivate the rear vents or perhaps some vehicles never had them activated.

Reading the manual, I still think it is very vague. I've seen the same detail in a tech' document for the E70 X5, which has a very similar system of 2-Zone or 4-Zone.

It references the deactivation from i-Drive, then reminds the tech's it is reactivated by the rear passengers, if they touch the controls. Hence why I say the instructions must be referencing the 4-Zone. 2-Zone has nothing to 'reactivate' in the rear, as the thumb wheels just have a mechanical flow rate control.

HighlandPete

[HighlandPete]

Originally Posted by lodewijkV

So, I did read this whole tread and I thought: it's time for a "heat-test-trip"!

My finding:
When the car is heating up there is hot air coming from all vents! Even from the rear center vent.
But after a while when the desired temp is reached the center rear vent starts to blow colder air. Which is actually completely normal in my opinion because the rear foot vents are still blowing hotter air, so the mix makes the perfect temp.

All IHKA systems I've driven do the same thing. Part of the programming to start warm and then regulate, when the car has built enough heat to start blending the face vent air flow.

My car (3-series) will change the centre face flow temperature at almost the same place along the road, every time I drive, across quite a wide ambient temperature range. The centre face vent, fine tuning wheel setting, can change that distance, and the resulting air temperature, once it starts regulating.

To me absolutely normal, the added advantage in the 3-series, the rear face vents have a heat adjusting thumb wheel, so there is also fine tuning for the rear passengers. That is what is missing from the 5-series 2-Zone. But you can specify a 4-Zone, for 'treating' the rear passengers.

HighlandPete

[desertking]

Originally Posted by Sharbotcom

So, for those who have the 2 zone system and apparently only get cold/cool air out of the rear vents housed in the centre console, try the experiment as described above (alternating your hand between the under dash vent in the drivers footwell and the rear centre console vents). The best measure would be done once the car engine has already warmed up and the centre dash vents (the ones controlled with the red/blue setting) is either set to be midway between red and blue or turned off completely. Force the system into a warming cycle by turning the heat up few degrees. If the expelled air in the rear continues to be cooler that the air expelled under the dash, then I would say you have problem. If it is the same then I'd say it is working as intended.

Bill

tried but nothing worked... gotta see my dealership very soon. this is a very frustrating fact. i hope they will resolve this nicely. If this works on your vehicle but not on mine, i see it as an issue.