[deepakita]

Got a quick question.
I have 07 323i in Japan and the AC behave little weird.

When I set the climate control to AUTO, car decides where to blow the air. When it's hot out, car first blows cold air mainly to cabin and a bit to my footwell. But then it randomly switches to front window and blows kinda hot air almost max power for up to 30 seconds, then slowly turns back to normal.

I know I should just select the cabin and footwell so that I don't have to be bothered, however selecting footwell makes my toe dead cold😭

Anyone got clue what's causing the situation? I ran the scan with PROTOOL and nothing AC related came up.

Thanks in advance.

[Brian86]

Probably normal. Does the car have a rain sensor?

It sounds like it's just trying to defog the glass. My car will abruptly do that when there is a wild temp/humidity mismatch inside to outside that causes sudden fogging, like pulling a cool car out of the garage into warm humid morning.

There may be some sort of gasket malfunction going on with the rain sensor causing it to see condensation where it does not exist on the portion of the glass you're looking through.

[deepakita]

hey Brian

Yes my car has a rain sensor.
Though the front window rarely gets condensation while driving in hot weather, now I'm assuming the sensor is sensing the condensation trapped inside the area.
Do you think heating the glass surface with heat gun and such would get rid of the condensation?

[Hoody007]

Originally Posted by deepakita

hey Brian

Yes my car has a rain sensor.
Though the front window rarely gets condensation while driving in hot weather, now I'm assuming the sensor is sensing the condensation trapped inside the area.
Do you think heating the glass surface with heat gun and such would get rid of the condensation?

Would not recommend doing that as you might damage the glass or cause the sensor to become unglued.

Do you see any condensation in the sensor area itself?

[Brian86]

Eh, I can't help much on troubleshooting. I've never removed the rain sensor.

It does fit the symptoms that some water vapor is behind the sensor, then the cooling interior of the car causes it to condense.

I would imagine there is some sort of vent to the interior built into the sensor. It might just be your local weather and an edge case on sensor calibration.

If it was me, I wouldn't mess with it until the seasons change.

[deepakita]

Brian, Hoody

I looked up at some videos on condensation sensor removal/installation and it looked rather simple and I've managed to take the sensor off the glass no problem.
I used dental floss wire instead of flat head screwdriver so that the glass wouldn't get any scratch or crack.

And no Hoody, I didn't see any condensation from the outside. But perhaps it was more humid inside the sealing/tape that it fogged up way before the actual window gets condensation.

Some people on forum said that those sensors are tacked on with double sided tape, so I'll reinstall it once I clean up the glass and sensor.

https://ibb.co/FWJL29d


Like Brian mentioned, this probably is the edge case as I live in the humidiest part of the world 😭

[deepakita]

So I went to hardware store to get a 0.6mm thickness double sided tape and stuck the sensor back on the glass.
AC would still blow to the window and problem couldn't have solved by simply reinstalling the sensor.
https://ibb.co/HdvQ84G

I took a closer look at the sensor which seems to have maybe a couple of layers of thin plastic films and thought that it has nothing to do with the condensation on the actual glass, but the sensor itself is faulty that it keeps sensing the condensation
at very high sensitivity.

instead of fiddling with this exact copy of sensor or purchasing a brand new sensor for $200, I simply disconnected the wire.
luckily I can see the window getting fogged up with my eyes, condensation sensor is now retired and will rest on the glass for the rest of its life.