[satz]

hi all

I believe my 2009 E90 has a condensation sensor mounted behind the rear-view mirror. It also has the auto climate controls. The instruction manual doesn't mention how this works.

I guess it detects condensation in the 'screen and then changes the airflow on the climate control towards the 'screen?

But.... does it also switch on the AC if it's not already on. And if it does, should the AC light also come on?

Related question... does switching on the windscreen defrost button also switch on the AC?

thanks

[Tom K.]

Isn't that a sensor for the auto windshield wiper setting? If so, it should not turn on the AC.

And yes, in my E91, hitting the front defrost button turns on the AC (light comes on), directs the airflow to the windshield and sets the fan to maximum.

Tom

[patents]

Modern auto or even manual hvac systems will turn on the ac compressor when in defrost mode. It dries out to air to help remove moisture on the windshield.

We don't know for sure the algorithm for the condensation sensor and controls, but I would think that turning on the ac compressor would be part of that program, along with temperature and directional control.

[patents]

Originally Posted by Tom K.

Isn't that a sensor for the auto windshield wiper setting? If so, it should not turn on the AC.

There's a separate condensation sensor near the rain sensor. It detects fogging and adjusts the hvac accordingly.

[kkasson]

See the section on the condensation sensor in this document: http://www.shrani.si/f/2z/Eu/2cbNKAh...te-control.pdf

[Tom K.]

Originally Posted by kkasson

See the section on the condensation sensor in this document: http://www.shrani.si/f/2z/Eu/2cbNKAh...te-control.pdf

Thanks for that post.

Tom

[satz]

thanks for that link kkason. That pretty much answers my questions. According to that link (is that some training manual for techs?)... it says that the condensation sensor directs air (but doesn't mention switching on the AC compressor).

LIkewise when activating 'defrost' button, it doesn't mention activating the AC compressor.

Kind of surprising when cars I've had going back 20 years (and much cheaper), do switch on the AC when you select windscreen defrost. But admittedly they were Japanese...

[NiNeTyOne]

kkasson,

Have any more of those documents? For instance on the braking system or the DSC systems? I'd also love any you have on the GL6 equipped X drive cars

[kkasson]

I'm not sure exactly where they're from or which ones exist. I've just found various ones on google. If you search for E90 on google and limit it to that domain, there are a few others. There are also pretty comprehensive documents on the N54 and N52. You can usually find them if you search for "technical training" or "technical document" or something like that.

I haven't seen one for xDrive but I'm sure it's out there somewhere.

The DSC/brakes document is here: http://www.shrani.si/f/1y/5A/2O3V7DU...iving-syst.pdf

[ptpending]

nope, e90 climate system can dry windshield using hot air too