Is it by design

[Rambam]

Was just wanting to confirm if this is by design.. In my 2001 E46 320i I cannot switch my rear de-mister on without my climate control coming on. is this how it is supposed to be or is there some way to switch it on by itself? It's a bit annoying for me because I get some static on my radio when my de-mister is on.

 

[Ephraimramodike]

I have the same issue on my 2001 E46 318i... I think it's a flaw... it shouldn't do that!

 

[Coisman]

My 325 2003 does the same, as soon as you put the demister on, the AC comes on at low.

 

[whattingh]

I have not confirm this but reason is ac dry out air which help the demist process.

I know some people in car without climate control they put on the ac and bit of heat. ac to dry the air and heat to break the cold of the ac

 

[dyllindd]

Mine also does that. :fencelook:

 

[Sankekur]

I don't think the AC should be turning on, but the fan/HVAC unit (whatever you call it) should turn on, as it helps with the de-misting of the rear window - have look at at the parcel shelf you will see that there are vents for the rear window on it.

 

[335i Lci]

:biglol: all are like that guys!

 

[Iceman007]

My 325 2003 does the same, as soon as you put the demister on, the AC comes on at low.

On mine The AC does not come on. omly if I Switch it on. Check my dads 318 2001 is the same as mine

 

[MikeR]

:rollsmile: by design....cold air works better

 

[whattingh]

why car mist up
Every time you exhale you introduce warm moist air into the interior of your car. If the window glass is cool that air condenses on the glass.

Once a window is misted the ac will be the fast way to get it demisted. No doubt.(test it if you dont believe). The ac dries out the air and also cools the air around the window so that the condensation does not happen.

The for a longer solution you need to put hot air on the window to heat it up so that it does not condense on it.

I have not try to confirm it yet but the bmw demist function i think starts with ac and recirculation. Slowly with time it also adds heat to the mix to heat up the window.

I my old jetta I had years ago I always start with ac and 50% heater. after a few minutes I would turn the ac off. and it always work.

 

[Sankekur]

One more thing that I can add about the e46 rear window demister is that it is pretty frikken useless for some reason, the one on my slOwPEL was better.

 

[moranor@axis]

its useless because the higher speed cools the window more :rollsmile:

 

[Sankekur]

its useless because the higher speed cools the window more :rollsmile:

:biglol: