that is controlled by the outside temp... it will blow hot air if its below 3 deg C.

At least thats what my manual told me

 

Outside temp was 9C so it should have been conditioned air. I'm wondering if the auto temp climate control sensor is bad?

 

Not sure what you mean... Are u pressing the defrost button? Shouldn't that air be hot anyways?

 

it always blows hot air onto the windscreen, i'm fairly sure it says so in the manual somewhere...but i might be wrong

 

mine is always hot even in the summer its so annoying

 

:werd:

same here its annoying as fack

 

How else do you remove frost and ice without warm air? It is called de-frost for a reason. :facepalm:

 

De-frost understood!

If you look at all BMWs I've owned none of them have done this.

In auto mode air circulates through all of the high, mid and low ranges of the air system, incuding defrost.

Outside temp, inside temp and humidity of the cabin dictates if your going to get fog, frost or whatever on the inside or outside of windows.

Temp outside yes below or close 32F of course ice, and that is what an ice scraper is for!!!:woot:

If your windows start to fog and temp and dew point is within a couple of degrees you get foggy windows or below freezing frost or if some idiots run with their recirculate on.:facepalm:

Not to mention if your defrost system is working it goes through the exchanger removing any moisture out of the air so you can defrost and it doesn't have to be hot air!!!

Why not try to be helpful vs. trying to be smart, especially when you have no idea what you are talking about!!:brent2:

 

:facepalm::facepalm:

 

Oh engineering STUDENT, understood, find another career:banghead:

 

Thanks for the fun facts, lol.

Here, I'll clarify and be more educational.

-So the defrost thing, you really can't deny me there. You need energy to melt ice, which is delivered in the form of warm air, and this is one of the functions of the defrost since not everyone caries an ice scraper. You can even read the manual which states "This program quickly removes ice and condensation that forms on the windshield and side windows." You turn it on, it loosens up ice, it wipes off with wipers much easier.

-As for removing condensation, well, it just raises the temperature of the glass slightly. Eventually this raises the temperature of the glass enough so that it won't cause air to condensate when it comes into contact with the glass. Since you are so knowledgeable on the subject, you should already know that the saturated vapor pressure of water changes depending on temperature. You should also know this is why when air contacts something cold, and cools down, the partial pressure of water stays the same, but saturated vapor pressure decreases. So if the partial vapor pressure exceeds the saturated vapor pressure, it becomes supersaturated, and the water in the air condensates and deposits itself. This is also why sometimes when turning on defrost will make things worse before they get better, because it takes time for the heat to warm of the windshield and the warm air will just deposit more moisture on the windshield until it warms up.


EDIT: what part of what I said was even wrong? :rofl:

 

My cars do the same thing (hot air on defrost). I think it's normal.

 

The hot air blows to make things evaporate easier. The A/C is on to dehumidify the air. They work together to defrost the inside of your windshield effectively. Tada!

 

also, whenever you have your wipers on, it blows a little warm air on the windshield. And i've noticed that if its raining out, i need my air conditioning on or it will fog up the inside of the windows, doesn't matter what temp though, it could be warm or cold.

 

When in auto mode, the top/defrost vents should not be blowing hot hair. It only blows hot air when in defrost mode. This problem can arise if the top/defrost vents are stuck open and it will continually blow hot air regardless of the temp setting. On my E46, none of the air flow control buttons (top, dash, bottom) were working and that was an indication that flaps were stuck in one state. I pulled my dash (there are some good DIY on youtube for pulling the dash and it was very simple) and removed the climate control unit. There is one small connector/cable that controls the servo motors for the flaps and when I disconnected and reconnected the cable, the flaps were working again. You can tell when it works because when you push any of the flow control buttons you can hear the motor actually turning if you listen really close. Not sure if this is your problem, but it may be worth a try. It saved me probably several hundred dollars in repairs.

 

Lol, this was the only real comment that made sense. Nobody was asking how defrost works. Seems like some e46s, (including mine) blow crazy hot air when defrost is on no matter what settings are on/off (I.e. temp setting, A/C on or off, cold hot dial, etc) And I’m hoping I have a flap issue as well. Yes, I’m sure hot air defrosts faster…..but In the winter when I have cabin at the temp I want, but windows start to frost, the defrost air is so hot it’s uncomfortable, AND EVERY OTHER CAR IVE HAD YOU COULD ADJUST THE TEMP OF THE DEFROST AIR OR THE DEFROST AIR DOES NOT IMPACT THE INSIDE TEMP OF CAR and blows air temp similar to that of set cabin temp…analogy would be similar to me walking into a hockey rink, and inside the building it is -10 degrees Fahrenheit, and I say “wtf, it is freezing in here!!” and a group of losers hears me and says, “duh it’s an ice rink, it’s supposed to be cold to keep the ice frozen”….just no.

 

no check fuse 46 and replace heater control valve if your heater is out of control.

 

Pretty sure it's normal, not too often I have to use it if it's warm outside anyway.

 

So I have similar situation that applies, maybe. I'll be very clear. 2002 E46 325ci vert. With AC on I get super cold air from middle air vents and hot air from window vents when middle button and top button engaged. When I turn off window switch, leaving only middle I get semi-coolair. It's as if the hot air is mixing with cold. When I engage middle and lower vent, I get super cold air from middle and hot air from lower.

Does this sound like a climate control issue as stated earlier??