FYI: correct setting of the HVAC

[Doru]

I found this on a different forum (it's for e46, but the function is pretty much similar). I thought I share with you guys. Here is the original thread, and below is the copied version of the OP:

"Since it seems like everyone in the world tries to use it a manual climate control, which it's terrible at, instead of automatic, which it's wonderful at, I thought I'd write a little guide

1) Choose the temperature you want the inside of the car to be. For most people this will fall somewhere between 67º and 72º. Personally, I'm most comfortable at 69º. The answer is NOT in the 50s or 90s (would you set your house thermostat to 91º? No, that would be ridiculous).

2) Set the temp display to your chosen 67-72º temperature.

3) Press "auto"

4) SET THE RED/BLUE DIAL TO THE WHITE LINE. AKA, it's purpose it not to be set to red in the summer and blue in the winter.

5) Press the recirc button until the left light is illuminated. That is the automatic position.

6) Done. Never touch it again, the car will take care of everything.




To clear up some misconceptions that seemingly everyone has:

1) setting the temp into the 50s will NOT make the car cooler any faster in the summer than leaving it on, say, 68º auto. The car will run the compressor and fan on full to achieve the target temp.

2) Similarly, setting the temp to 90º will not make the car get warm any faster in the winter. The car will crank the heat as soon as the heater core is generating enough heat for it to be beneficial to do so

3) The red/blue/white dial. 98% of the time, the correct position is the middle (white line) position. If you think the e46's climate control sucks (it doesn't), it's probably because you've messed with that dial. The purpose of the dial is to control the temp of the air blowing on your face beyond the climate control program. Good examples of when it can BRIEFLY be useful to tweak it: You just left the gym and you're overheated-- set to blue till comfortable, then back to white. Or, you just went trekking through the snow for days and need hot air directly on your hands and face-- set to red till comfortable, then back to white.

The default behavior of the dial is to blow cool air on your face while keeping the car at a comfortable (your chosen) temperature. Cool air is statistically proven to keep you more alert when driving, which is why this is done. On particularly cold mornings it will automatically blow warm out there till the cabin is warmed up, so there is no need to tweak it for that.

4) DO NOT TURN OFF THE AC COMPRESSOR. In the winter. In the rain. In the summer. In the fall. In the spring. In the winter, the AC compressor acts as a dehumidifier. Ever wonder why your windows fog up an other people's don't? It's because you turned off the AC compressor so your cabin is full of humidity. Same thing in the rain. It continually blows my mind how many people I see driving around in the snow/rain with their windows cracked and car fogged up, trying their hardest to see and not knowing that they are the cause of their own problems. Oh, and the AC compressor automatically disengages when your floor it, so it's not going to cost you any acceleration, either. Also, the AC compressor gets lubed through use, so not using it for long lengths of time will lead to premature failure. And, the car is less fuel efficient above 40 mph with the windows down and ac off than it is with the windows up and AC on, so you're not saving any gas, either.

5) The recirculate button. Three settings-- recirc, auto recirc, and no recirc. Auto recirc detect man made smells (chemicals, exhaust) and will automatically put the car in recirculate mode. 99% of the time, that's the mode my car is in. The exception is that it can't detect biological smells (e.g. rotting dead animal, skunks, etc). If you're going to be stuck next to one for a while, probably behooves you to put it on recirc for the duration.

6) unless you have specific reason to do so, don't direct where the air is flowing (as in, leave the lights on feet/face/dehumid on the left turned off). The car will move air about automatically as required.



So, to recap-- choose your temp, press auto, recirc in auto, snow flake on, dial to white, and stop touching it.

Used properly, the e46's climate control is pretty excellent. It can keep you comfortable year round without you ever having to touch it. In fact, the ONLY downside I can think of is there's no one touch off button.

Used manually, or trying to out smart it, it's a terrible system that constantly needs tweaking."

[tmv]

Good to know. Thanks for sharing Doru.
I did most of it before knowing it, except the dial in the center vent.

[Ricky Bobby]

The only thing I think is different is the red/blue dial does not have a white line on our cars, I'll check mine at lunch but I think it goes 1,2,3 blue dot then 1,2,3 red dot.

I'll remember the tip about auto recirculate, but I usually leave recirculate off unless I am rolling through a dusty/smelly area, I would rather pull the fresh air in if possible as opposed to recirculating the air already in the car (i.e. in summertime recirc is the worst because the car is trying to bring down the 100+ degree inside air down to a cool and comfortable 70 degrees, as opposed to bringing in ambient air at 85-95 degrees and cooling it, makes the system work harder and longer)

[racingbmwm3]

Repair tip: After major cooling system work or major coolant loss, before refilling the system, I recommend turning the temp for both sides to 90 and turning the fan speed to low with the key on. Then refill. This will open the heater core and operate the auxiliary water pump. You'll get air bubbles out of the cooling system faster and also prevent air bubbles in the heater core.

[JCL]

I agree with practically all of the original post, but there is an inconsistency. If you leave the centre thumb wheel at the white line, you will get the same temperature air blowing out as is blowing out the other vents. It might be cool, but it might be warm, depending on what the HVAC system is trying to achieve at that moment.

I agree with the benefit of cooler air in my face, to stay alert. For that reason, I leave the thumb wheel on one blue dot (which means one degree cooler). If I left it on the white line, I wouldn't get the benefit of cooler air on my face. The white line setting is for those who don't want the cooler air out that one vent.

There is another subtlety that isn't addressed. My X5 had a fully automatic setting (as described in the post) but as I recall it also had a type of semi-automatic mode, in that you could let the system decide the ratio of top vent/bottom vent and you set the fan speed, or you can adjust the vent mixing and let the system choose the fan speed. In extreme climate conditions (ie -30C) the automatic mixing wouldn't keep the windshield clear. I could either prioritize the windscreen vent over the other vents, or I could boost the fan speed. The former allowed me to keep it in automatic mode as I recall.

[racingbmwm3]

Originally Posted by JCL

There is another subtlety that isn't addressed. My X5 had a fully automatic setting (as described in the post) but as I recall it also had a type of semi-automatic mode, in that you could let the system decide the ratio of top vent/bottom vent and you set the fan speed, or you can adjust the vent mixing and let the system choose the fan speed. In extreme climate conditions (ie -30C) the automatic mixing wouldn't keep the windshield clear. I could either prioritize the windscreen vent over the other vents, or I could boost the fan speed. The former allowed me to keep it in automatic mode as I recall.

Yes, starting in full auto mode and then adjusting the fan speed manually, the system still automatically regulates the vent distribution. Or, starting in full auto and then pressing one of the vent modes, system still controls fan speed.
Also, the AC compressor will not activate at low ambient temperatures to protect the system from damage because of frozen refrigerant.

[powers1]

Same as Ricky Bobby and Jeff ,here!Mine doesnt have a white line,so I just keep it on one blue dot.Great post in general,thanks for sharing.

[Qsilver7]

Originally Posted by JCL

...There is another subtlety that isn't addressed. ... as I recall it also had a type of semi-automatic mode, in that you could let the system decide the ratio of top vent/bottom vent and you set the fan speed, or you can adjust the vent mixing and let the system choose the fan speed.

I understand what you're referring to...and the e46 forum member didn't mention it in his write up...though he did a very good job in explaining what some BMW owners seem to find confusing.

I'm not sure though, if the AUTO air speed remains on if you change the air direction button from AUTO to windshield/dash/floor...I'll have to play with that on the way home if I remember. { EDIT: it took me so long to get this together...looks like racingbmwm3 answered this one. }

There are 2 AUTO programmings if you have the IHKA control panel...

1. air direction - you have the defrost/dash/floor vents...AUTO will send air through the vents based on its own algorithm...but the driver can make a manual selection of windshield (defrost)/dash/floor...and the passenger (in the e38) can select the dash or floor.
2. fan speed - when in AUTO mode...the word AUTO will appear in the fan speed display...if the fan speed button is pressed, the system will go into manual fan speed mode based on how many dashes "- - - -" appear in the display...to return to AUTO fan speed mode...press the AUTO button on the IHKA until you see AUTO appear in the fan speed display again.

This topic is covered also in the owners manual on the page below (just an FYI for those that forgot or didn't know.

The other thing that wasn't covered were the IHKA's pre-programmed settings MAX/REST/Rapid-DeIce-DeFrost. The latter (rapid defrost) confuses many BMW owners across mutilple models...they wonder why they can only get high heat at high fan speed velocity when they want to defrost/de-ice the windows...not knowing that the button they keep pressing is for RAPID DEFRSOTING...and if they want to control the air temp and speed, all they need to do is press the WINDSHIELD (upper button) on the IHKA control panel to send air directly to the windshield.


Those with the MAX button on their IHKA control panel have a preprogrammed cooling mode when temps are above 61 degrees (F)...and a warm mode (REST) when temps are BELOW 59 degrees (F). Those with a REST button only ... only have the warming mode :

The AUC system (as mentioned by the e46 thread) is the auto recirculation mode. You can get fresh air all the time, recirculated air all the time (not good for you), or an auto recirculation mode that utilizes the AUC sensor up near the radiator:

[motordavid]

Maybe it's just me, but I find the 'manual' approach to HVAC settings/use to be fine and very workable...

When I first got the X back in 9-2001, I read the umptyseven page manual a few times, played with 'Auto' settings for awhile and then retrograded back to 'manual'.

I have read the advice to keep the 'air' on 24/7, etc, etc.
But, I still like manual settings, (temp, vent(s), A/C on or not), and it works well for me.

Nice thread though...
GL, mD

[JCL]

What I have found interesting in 8+ years on this board (and this topic has come up many times) is the number of owners who say that the E53 HVAC system is the worst they have ever seen, doesn't work at all, etc. I found it worked just fine, but by coincidence I seem to have used it similarly to how the design engineers envisioned it, set it and forget it. I never turned the AC off in 4+ years, I never changed the auto recirc once as far as I remember, and I found the thumbwheel for temperature offset through the dash vent to be logical.

If it works for any owner in manual mode, I think that is great. More power to them. I do think that many people who got frustrated with it tried to live somewhere between auto and manual, and ended up fighting it, by using the thumbwheel as a proxy setting for desired air temp for example.