Blend door help?

[Henway]

I've gone to the FAQ and it wasn't super helpful about what to prepare for. And I tried searching and wasn't successful--this website's search function often doesn't give any results--"blend door" in title in Z3 group was 0 discussions. (please reply with a good web address of the discussion if you can find it)

My heater dial moves very slowly and doesn't want to stay in one spot (except for full-cold), even holding onto it for a mile on a bumpy highway. The hotter the temp I try to dial in, the less likely it is to stay.
AC cooling works great but very little heat, so it's a bit cold now.

I think it's not likely to have broken ball-heads.

What am I looking at for time and parts?

Might this be an adjustment from the passenger-side footwell?

If not, what parts should I buy beforehand--or do I need to really get in there to determine what's going on?

It's a second car, but will me getting halfway into this make it undriveable until it's fixed?

Final question--it's usually parked with a wall on the passenger side. Will I need to have access getting in through the passenger door?

[Vintage42]

... My heater dial moves very slowly and doesn't want to stay in one spot (except for full-cold)... Might this be an adjustment from the passenger-side footwell?... will me getting halfway into this make it undriveable until it's fixed?... Will I need to have access getting in through the passenger door?

Here is a blend door cable DIY:
https://www.bimmerfest.com/forums/sh...5&postcount=11
You would need to work through the open passenger door. Even it you stopped with the glove compartment out and cable disconnected, the car would be drivable.

I think the problem is that the blend door has a foam gasket with adhesive backing. The foam disintegrates, causing the door to stick to the adhesive. The resistance causes problems like the ball pin in the knob breaking off, or the cable coming out of adjustment.
Here is an interesting thread showing foam gasket:
https://www.bimmerforums.com/forum/s...adding-is-this

[Henway]

Based on this assumption, am I'm looking at taking off the entire dashboard?
I've only heard how much of a PITA this is. Any idea how long to expect to do it?
Are there other worries for doing it--what is likely to break in my beige interior?

[Vintage42]

... am I'm looking at taking off the entire dashboard? ...

Did you even look at the link in Post #1?
https://www.bimmerfest.com/forums/sh...5&postcount=11

[Henway]

Yes I did, and that failure mode is different (that one is stuck near cold--mine gets stuck at 1pm and farther clockwise).

[Randy Forbes]

I think the fault lies in leaving the door fully closed for extended periods; leave the door in an intermediate setting, and make it a point to exercise it often.

(agreeing with Vint that the foam disintegrating into goo is the root cause)

[Henway]

Should I be replacing light bulbs or anything else if I'm going to dig in that far to fix this?

[rasmuw]

You could reach some light bulbs in the center console, but that’s the hard way. If you have the glove box sag, you should address it. I hope you don’t have any broken plastic tabs and large holes where the under dash panels attach.

[Vintage42]

Yes I did, and that failure mode is different (that one is stuck near cold--mine gets stuck at 1pm and farther clockwise).

I think it would be worthwhile to see what the blend door cable is doing in response to the control knob. It is rather easy to look at per the DIY, as a first step.
Going into the console and removing the control panel is considerably more difficult, and does not fix anything that might be wrong with the cable or blend door;

[Henway]

Yes, I'll try the cable first--I believe it has to be removed anyway to get to the dash.

[Vintage42]

Yes, I'll try the cable first--I believe it has to be removed anyway to get to the dash.

I don't think it does. And you would be going into the console through the radio hole, not involving the dash.
This post talks about the cable end and the control end:
https://www.bimmerfest.com/forums/sh...69&postcount=2

To look at the cable end, I think you will need to remove the glove box which the link in Post #2 does not mention. This post has links for glove box removal. Be sure to rotate the passenger side of the box downward to that its forward screw tab is rotated with minimum stress up and over the side of the console. The forward tab is the hardest one. If the tab breaks, you will have a fiddly repair.
https://www.bimmerforums.com/forum/s...0#post26347650

1 Removing glovebox.jpg

If you do need to go into the control end, here a thread on that. But If your cable moves some, I don't think the problem is in the control end.
https://www.bimmerforums.com/forum/s...ntrol-knob-fix

[Henway]

I accessed the bowden at the bottom and forced the door all the way open (full hot) and it now will move mostly smoothly and go all the way to hot without problem. If I go to cold it wants to stick there, but now at least it will go to all hot (the wire hiccups 7/8 to full hot but then will go all the way). I'll keep exercising it before putting it back together. Does this mean it's fixed?
Also, the cover (the latch cover on the car side of the glove box #51168410477) was mostly broken and then crumbled apart. Should I make a metal replacement or should I get an OEM one--it seems like it's in a place with higher stress than BMW anticipated and likely to break again--am I wrong?

[Vintage42]

... If I go to cold it wants to stick there... I'll keep exercising it before putting it back together. Does this mean it's fixed?
Also, the cover (the latch cover on the car side of the glove box #51168410477) was mostly broken and then crumbled apart. Should I make a metal replacement or should I get an OEM one...

Exercising will just keep forcing the blend door into to adhesive residue on the box, left after the foam tape disintegrated. That will stress the cable and the knob. I don't move that knob all the way.

The flimsy latch cover breaks easily if tightened, mine did:
https://photobucket.com/gallery/user...Mzk0NDc=/?ref=

I ordered a new OE cover plate and was very careful when tightening:
https://www.ecstuning.com/b-genuine-...r/51168410477/

The cover can only be replaced by going as far as the sagging lid fix. I bought the usual sag kit and it was too cheap and crude:
https://www.ebay.com/itm/96-02-BMW-Z...YAAOSwHnFVnYyW

So I solved the sag just by removing weight from the box. The steel USA crash plate inside the lid, and the folder of manuals, weighed 4 lbs, more than the Euro designed "glove" box was designed to support. But in case I ever wanted to use a sag fix kit, I then bought and stored this one as the very best, not only because it *includes* a custom made sturdy metal cover plate:
http://www.donewhenimdead.com/garage...8cbzkz5vndx31a

Your cover plate is broken, and your box may be sagging. Why not go for that best kit.

[Vintage42]

.

[Andy Woods]

I installed that same kit. Cost a little more but very well made and worth the money, imo.

Sent from my SM-J327V using Tapatalk

[rasmuw]

+2.

[Henway]

Understood--there is a flimsy strengthener the PO installed which did an acceptable job of fixing it, but I might as well spend extra money for better if I'm already there.
I take it this means I still need to remove the entire console to get to the blend door for proper fixing?

[Vintage42]

... there is a flimsy strengthener the PO installed which did an acceptable job of fixing it... I take it this means I still need to remove the entire console to get to the blend door for proper fixing?

What is this strengthener and what did it strengthen?
I think the blend door is inside the HVAC housing, between the evaporator and the heater core.
Here is a drawing of the housing, which probably needs both the console and dash removed to access. I have not heard of anyone getting inside of it.

HVAC Housing.jpg

Here is a picture of the openings in the top of the housing, showing the defroster doors on each side, with their stuck-on foam gaskets. They may be similar to the blend door.

[Henway]

The strengthener is what the latch cover screws into on the door and is similar to the one in the kit from Never Done. Yes, the insulation in the picture seems to be the culprit for most of our problems, if what I'm reading is correct. Getting at it to remove it and replace will require how many hours?

[Vintage42]

The strengthener is what the latch cover screws into on the door and is similar to the one in the kit from Never Done. Yes, the insulation in the picture seems to be the culprit for most of our problems, if what I'm reading is correct. Getting at it to remove it and replace will require how many hours?

OK, you were referring to the glovebox metal support bar, and the hvac blend door, and the combination confused me. If the glove box "strengthener" was flimsy, then it was the original thin spring steel. The sag kits use a thick crudely made bar.

The disintegrating foam in Post #18 is between the hvac housing box and the dash, and it can be replaced by removing the dash. A forum member recently did it. Here is a photo showing the exposed housing:

Z3 Dash Removed.jpg

But you want to get inside the hvac housing box, which I think is where the "blend door" is, which I don't think anyone has done.
I would just leave the blend door alone and simply don't turn the knob all the way.

[Henway]

Good to know--I'll just live with it and put the temp to the middle when I park it every time. It is what it is. I ordered the aftermarket strengthener this morning.