Ventilation system: vent selection issue

Juggernaught5 · 06-01-2015, 12:32 AM

Hi All:
I'm having an intermittent issue with the ventilation system. I always have the vent selection choice set to the dash vents. Occasionally, after starting the car, the air will start blowing, but out of the windshield vents (with the selector knob still on the dash vents). To correct this, I have to cycle through the vent choices until the dash vents "kick in." There's no issue with fan speed or air temp - just the vent selection.

Of note, I have noticed a chunk of foam-like material in my driver's side vent above the cup holder. I tried to pry it out, but it breaks down. It's about 1/2 square.

Can anyone help me diagnose?

elerner61 · 06-01-2015, 10:59 AM

When you notice the air coming out of the windshield vents, is the HVAC in "Auto" mode? Either you are putting it in Auto mode and not remembering/realizing, or perhaps it is going into Auto mode by itself and you have a buggy HVAC control.

Juggernaught5 · 06-01-2015, 02:57 PM

Quote:

Originally Posted by elerner61

When you notice the air coming out of the windshield vents, is the HVAC in "Auto" mode? Either you are putting it in Auto mode and not remembering/realizing, or perhaps it is going into Auto mode by itself and you have a buggy HVAC control.

I don't use auto mode too much, and right now occurrence varies. When I start the car, the air will come on, then switch from only the dash vents to only the windshield vents, with the rotary knob never being moved and still on the dash vent setting.

Incompatible · 06-04-2015, 10:04 AM

Maybe related to your issue: I've always used mine on manual and once in a great while the change over from one vent to another is slow. My guess is the diverter plate (gate) or linkage is a little sticky. All I do is to cycle through all the vents with the fan on high a couple of times and the problem is solved for 12-18 months. Being in SoCal, rarely do I change any of the controls and suspect the lack of use is a contributing problem. It has done this since new (single owner) and has stayed the same over the years.

I wonder if the foam seal is/was limiting full positioning of the gate and somehow the electronics are going to a default setting?

Nate4641 · 06-04-2015, 05:52 PM

Possibly another related issue I've been having since I got the car. I can select just the dash and I can select just the floor and it will work fine. If I try to go to the middle of these two I get dash and windshield every time.

TommyA · 06-04-2015, 06:59 PM

I have noticed that there was a piece of insulation in the vent on the driver side as well. I just stick something small enough to try and break it up so it will blow out of the vent, I don't think there is anything to worry about.

WAMz4 · 06-05-2015, 01:10 PM

Must just be the car.
I always leave the vents set to dash vents, sometimes when I first get in, the fan is blowing at the set level but air from vents is low, as if it were re-directed. I have to move the vent slector to a different region and wait for it to blow full, then move back to dash selection to get full air flow back to dash.

06-01-2015, 12:32 AM	#1
Juggernaught5 Enlisted Member 1 Rep 36 Posts Drives: 2006 BMW Z4 3.0si Roadster Join Date: Feb 2014 Location: Phoenix AZ iTrader: (0)	Ventilation system: vent selection issue Hi All: I'm having an intermittent issue with the ventilation system. I always have the vent selection choice set to the dash vents. Occasionally, after starting the car, the air will start blowing, but out of the windshield vents (with the selector knob still on the dash vents). To correct this, I have to cycle through the vent choices until the dash vents "kick in." There's no issue with fan speed or air temp - just the vent selection. Of note, I have noticed a chunk of foam-like material in my driver's side vent above the cup holder. I tried to pry it out, but it breaks down. It's about 1/2 square. Can anyone help me diagnose?
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06-01-2015, 10:59 AM	#2
elerner61 Major 157 Rep 1,107 Posts Drives: '07 Z4M Roadster Join Date: May 2011 Location: Mount Kisco, NY iTrader: (0)	When you notice the air coming out of the windshield vents, is the HVAC in "Auto" mode? Either you are putting it in Auto mode and not remembering/realizing, or perhaps it is going into Auto mode by itself and you have a buggy HVAC control.
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06-04-2015, 10:04 AM	#4
Incompatible Major 55 Rep 1,224 Posts Drives: 07 AW Z4C 3.0Si Join Date: Aug 2007 Location: San Diego iTrader: (1)	Maybe related to your issue: I've always used mine on manual and once in a great while the change over from one vent to another is slow. My guess is the diverter plate (gate) or linkage is a little sticky. All I do is to cycle through all the vents with the fan on high a couple of times and the problem is solved for 12-18 months. Being in SoCal, rarely do I change any of the controls and suspect the lack of use is a contributing problem. It has done this since new (single owner) and has stayed the same over the years. I wonder if the foam seal is/was limiting full positioning of the gate and somehow the electronics are going to a default setting? __________________ If you can't take the time to teach a kid something good, someone will take the time to teach them something bad. Last edited by Incompatible; 06-04-2015 at 10:12 AM..
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06-04-2015, 05:52 PM	#5
Nate4641 Major 151 Rep 1,134 Posts Drives: '07 M Roadster Join Date: Dec 2011 Location: Warner Robins, GA iTrader: (0) Garage List 2007 BMW Z4 M Roadster [0.00]	Possibly another related issue I've been having since I got the car. I can select just the dash and I can select just the floor and it will work fine. If I try to go to the middle of these two I get dash and windshield every time. __________________ My build/adventure thread
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06-04-2015, 06:59 PM	#6
TommyA Enlisted Member 3 Rep 34 Posts Drives: 2007 Z4 3.0i Join Date: Oct 2014 Location: Atlanta Ga iTrader: (0)	I have noticed that there was a piece of insulation in the vent on the driver side as well. I just stick something small enough to try and break it up so it will blow out of the vent, I don't think there is anything to worry about.
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06-05-2015, 01:10 PM	#7
WAMz4 First Lieutenant 45 Rep 384 Posts Drives: 2006 Z4 3.0si Roady Join Date: Mar 2009 Location: Denver CO iTrader: (0)	Must just be the car. I always leave the vents set to dash vents, sometimes when I first get in, the fan is blowing at the set level but air from vents is low, as if it were re-directed. I have to move the vent slector to a different region and wait for it to blow full, then move back to dash selection to get full air flow back to dash. __________________ The Internet said it. I believe it. That settles it!
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