DIY: How to fix air blend door MK4 TDI no cabin heat problem

Shizzell

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Aug 15, 2010
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US
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2000 Golf 1.9L GL 2dr
DIY: How to fix air blend door MK4 TDI no cabin heat problem

Problem:
I was not experiencing cabin heat at any point during my commute. This was becoming a serious concern not only because I was freezing, but also because I couldn’t defrost.

The coolant temp sensor said a solid 190. I knew my temp sensor was good as I replaced it recently, and the thermostat was also fairly new. I had installed 2 plastic sheets in front of my radiator to reduce air flow. The bottom cover of the engine was intact, and I re-insulated my top engine cover as the foam was not present.

I was not seeing any foam coming out of the vents, but since heater cores aren’t typically faulty, and my directional heating/cooling was not functioning, I decided to attempt a blend door repair without removing the dash.

I followed this on VWVortex, but hopefully I can clarify a few things in the procedure that may help others: http://forums.vwvortex.com/showthread.php?5984439-Mk4-blend-door-foam-repair-diy

Parts:
Aluminum insulation tape
Cleaning solvent
Miscellaneous torx, phillips, and flat-head drivers
Dremel

Procedure:
1. Remove plastic paneling under the driver’s side.

2. Remove the center console.

3. I got away with not fully removing the glove box, but it would probably be easier to just get it out of the way when you take the center console out.

4. Remove the center trim around the radio and HVAC controls.

5. Remove the controls and push them into the driver’s side foot bay.

6. Remove the radio and connections.

7. There are multiple hex head 8mm screws that hold down the vent casing behind the radio and controls. I could not get any sort of tool in there with a plastic corner that holds a radio wire bundle clip. I used a Dremel to cut the plastic out so I could get a straight angle on the screw.

8. I didn’t fully remove the vent case, so I just pushed it down far enough so I could reach inside the heat exchange.



9.
To access the doors, you must move your HVAC direction controls. I used a solvent to clean off the doors. Cutting length size pieces of tape, I was able to get one hand in there to attach them to the 3 doors. I used approximately 4 strips per side, per door. I was careful to make sure the tape didn’t rub on the door pathway when I moved the HVAC controls.

10. I cleaned the center piping going out to the cabin, and noticed that the piping was not attaching well to the airway. I taped the two plastic pieces together as I was re-assembling.

11. Install HVAC controls, radio, and trim. Install the center console and glove box. Install the rest of plastic.

The car begins heating immediately. I can tell the air recycling button does a lot more, and I can successfully direct air to my feet or my dash.


Cheers
 
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ericas_beetle

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Mar 17, 2011
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austin
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2000 New Beetle
Wow, I'm really excited about possibly being able to fix this. I've had foam blowing in my face for 3 years now, and worse, I've found if it blows out the defrost and lands on the dash on a hot day and I don't get it off immediately it becomes a permanent part of the dash :(

Does anyone know if this is doable for a Beetle? I read both this and the original thread and it only talks about Jetta.

Call me suspicious but I have to wonder why VW decided to put holes in the doors, and why they chose to cover the holes in foam. I guess the answer to the first question could be to make the door lighter so that it wouldn't put extra stress on the operating mechanism...maybe. But why cover it with non air tight foam? As porous as that stuff is, even with two layers as it appears to be, it would still let some small amount of air pass through.

I'm wondering whether this was a conscious design decision to prevent excess pressure which might cause the blower to prematurely fail, or to prevent excess sound from escaping air as it could blow the door open slightly and cause wind around the door? It also seems like it would cause more stress on the door flap mechanism if you changed the setting with the fan on high.

I'm just thinking out loud here, and wondering whether fully enclosing the door with aluminum tape is necessarily the best idea. Could anyone who has done this comment on any changes in sound or operation that might indicate a problem?

Also, yes, I have really anemic heat, but also I've never really felt like my AC was quite as cold as it should ideally be. Will this fix both problems or is the AC issue completely separate? Every other aspect of my AC operation has been checked out already.
 
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Shizzell

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US
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2000 Golf 1.9L GL 2dr
4-6 hours seems reasonable.

If you have the manual HVAC cable controls, you may just want to check ETKA and see if your exchange is the same part (or similar).

I'm not worried about stress on the door flap at all. I tested my A/C and it dramatically improved. I've also noticed that the car is *slightly* quieter when recycling is on, and outside fumes can be kept better at bay.
 

RockRockRock

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Aug 13, 2008
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So Socal
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2015 GSW M6
My guess is the foam is meant to allow ventilation. I notice that if i leave the vent selector on floor, the car has a slight mildew smell on some days. If I leave it on defrost, there is no smell since the moisture can evaporate unimpeded.




Sent from my iPhone using Tapatalk
 

Enabled

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Apr 23, 2013
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Houston, TX
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2003 Jetta TDI Manual, BMW 328d SW
Just so you know, this fix (a disgusting one, EXTREMELY poor design choice on VW's part) helped my air conditioning blow a whole lot colder.

Win win win. Hot air in winter, cold air in summer,... and best of all, no foam projectiles into your mouth, eyes, hair, etc.
 

Enabled

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2003 Jetta TDI Manual, BMW 328d SW
By the way, I used high quality HVAC aluminium tape which has adhesive that resists heat and cold changes, so it doesn't unstick itself.
 

autdi

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Nov 11, 2004
Location
Alabama
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2000 NB, 2003 NB, 2006 Touareg, 2015 Jetta, 2015 Jetta
Is this the same for the NB? 2000 has been blowing foam bits for a year now, A/C is meh, nearly no heat except on recirculate, so this needs doing. What I'm seeing are all Jetta or Golf models in the pictures and descriptions, and haven't looked at Bentley yet. The 2000 needs some love put into it, it's been the workhorse for a long time, but sits a lot more now that there are others newer around.

EDIT: Found a youtube video showing the procedure, looks similar enough to proceed cautiously.
 
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deejaaa

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Apr 15, 2007
Location
Baytown, Texas
TDI
FOR SALE, 2002 Jetta GLS, 5 speed
http://www.mcmaster.com/#catalog/120/3574/=twr0ip

I ordered this foam from McMastercarr adhesive backed, 1/8 thick extra firm foam

Extreme-Temperature Textured Silicone Foam, Adhesive-Backed, 1/8" Thick, 12" x 12"
looks like good stuff. did you read the fine print?:
"Foam only (not adhesive) meets ASTM D1056 2A3. Material has a skin on all sides. Adhesive is acrylic and has a temperature range of –20° to 180° F. Width tolerance is ±0.15". Length tolerance is ±3" for 3-ft. lengths and ±6" for 15-ft. lengths."
i think i have a few things i can use in the shop, when, if, i get to it.
 

tongsli

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Jan 31, 2000
Location
Baltimore, MD
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2000 Jetta TDI, 2004, Jetta Wagon TDI PD
looks like good stuff. did you read the fine print?:
"Foam only (not adhesive) meets ASTM D1056 2A3. Material has a skin on all sides. Adhesive is acrylic and has a temperature range of –20° to 180° F. Width tolerance is ±0.15". Length tolerance is ±3" for 3-ft. lengths and ±6" for 15-ft. lengths."
i think i have a few things i can use in the shop, when, if, i get to it.
I did see that and was thinking that i'd supplement the adhesive. I'm not sure my heater box gets to 180F. I doubt the OEM adhesive goes much above that temperature. So I think it'll be ok

Here's a 3m product that might work, at 550degs

http://solutions.3m.com/wps/portal/...ransfer-Tape-9082?N=5962555+3294274447&rt=rud

UPDATE: I ended up returning the foam above and re-ordered a less dense Silicone Foam. Much better stuff. I may go with the aluminum tape and foam on the edges combo like I've seen guys do on the Vortex.

http://www.mcmaster.com/#catalog/120/3574/=tyxqfh



 
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psulik1

Active member
Joined
Aug 24, 2014
Location
Chicago
TDI
2003 Jetta GLS
Hi, I just did this and wanted to offer my notes for anyone that may take a stab at this.

First it took me start to finish about 4 hours, I am not a mechanic but I know my way around a bit.

After all the controls/radio etc. were removed I got to the box. I didn't remove any screws or nuts like people mentioned, I just started prying and working the tabs and just worked my way from the sides/bottom and up. Took some careful prying but I got it. I didn't remove the back half, that's what the screws/nuts hold but I didn't see it necessary. I then cleaned the doors and applied the aluminum tape that was mentioned. It was mostly blind application because most of the doors are out of sight but I put a lot on trying to work my way from the top to the bottom, lots of overlap, I figured a little more may go a long way.

Snapped and assembled all back together and sure enough heat!

Not that I am an expert but if anyone ever has any questions feel free to contact me via PM and I would be more than happy to answer questions via phone or email.
 
Last edited:

jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
Hi, I just did this and wanted to offer my notes for anyone that may take a stab at this.

First it took me start to finish about 4 hours, I am not a mechanic but I know my way around a bit.

After all the controls/radio etc. were removed I got to the box. I didn't remove any screws or nuts like people mentioned, I just started prying and working the tabs and just worked my way from the sides/bottom and up. Took some careful prying but I got it. I didn't remove the back half, that's what the screws/nuts hold but I didn't see it necessary. I then cleaned the doors and applied the aluminum tape that was mentioned. It was mostly blind application because most of the doors are out of sight but I put a lot on trying to work my way from the top to the bottom, lots of overlap, I figured a little more may go a long way.

Snapped and assembled all back together and sure enough heat!

Not that I am an expert but if anyone ever has any questions feel free to contact me via PM and I would be more than happy to answer questions via phone or email.
I am familiar with the HVAC aluminum tape. So you didn't use any foam after you used the tape on the door panels?
 

Jesse_Boyer

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Aug 16, 2007
Location
Sioux Falls, SD
TDI
I'm all out...
All: I've done this on 4 cars by pulling the dash and one via the shortcut method. Only one car had the HVAC box removed entirely, the other 4 done in-car. All using using high-heat aluminum tape with decent success, no replacement foam. (granted, I likely never had a car with fully intact foam and cannot tell you how it should feel.) Anyway, on the 'shortcut car' I had less heat than desired, A/C wasn't as cold as desired. I wanted to make sure the air-flow was sealing properly between the doors and case for temperature control and directional purposes; I re-did the 'shortcut car' on Saturday. This car hadn't been directing airflow well and I wanted to investigate. While this can be done via shortcut method, I'll tell you where I went wrong when I did it. Learn from my mistakes. :)
.
First big error:
I failed to get the center vent blow-molded plastic snapped properly to the HVAC box on the top. This has to hook at the bottom of the HVAC box, slide into the plastic directional elbow which feeds the vents, and snap to the tab on the top of the HVAC box. The 'tab' which retains it folded over on itself and held the two sealing surfaces apart. Not only did this slightly warp the plastic piece, but it obviously didn't seal against the box, causing a great deal of airflow to leak into the dash and not be directed to the vents. Note this when you're re-installing. That tab needs to lock onto the heater box (all while fitting inside the components above to direct airflow to the vents.)
.
Now, the tape-vs-foam debate. The aluminum tape will certainly block the holes in the doors, but it won't seal around the perimeter. This is why I like the foam method better. You're able to seal VERY well between the case and doors when they're closed. Its still tight, but you can put the foam over the 'edge' of the door with the door partially opened and use your fingers to 'bend' it around to the other side. The top and bottom of the doors, use your best judgement to add a little extra foam beyond the door (1/8"-1/4" above.) This creates a foam edge that seals against the plastic HVAC box, sealing very nicely. (don't over do it or the door won't seal on the other surface, creating a gap.) One later of 1/8" foam did the trick nicely. In my opinion, the car has an insane amount of airflow compared to my wife's ALH which I fixed with just aluminum tape, no foam. Fan setting one with all the air-flow out the vents is almost excessive.
.
Personally, I'd rather pull the dash to have a little better access for blend door foam application, have access to replace the foam between the dash and defrost vents, the dash and center vents, seal a little better between the ductwork for the rear vents, etc.
.
This is the foam I used for the door foam:
http://www.menards.com/main/plumbin...n/foam-tape-1-8-x-2-x-30/p-1462837-c-8589.htm
.
For the ductwork connections, I used a closed cell 1/2"x1/2" meant for sealing around doors, windows. Similar to this stuff, but I thought it was 1/2" x 1/2":
http://www.menards.com/main/doors-w...l-foam-tape-weatherstrip/p-1914344-c-3624.htm
 

DanVito

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Sep 20, 2008
Location
Lakeland, FL
TDI
2004 Jetta Wagon, BEW, 242k miles & counting
Tongsli: What are the specifics on the foam you ordered, i.e. thickness, density, sheet size?
 

tongsli

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Jan 31, 2000
Location
Baltimore, MD
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2000 Jetta TDI, 2004, Jetta Wagon TDI PD
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Jesse_Boyer

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Aug 16, 2007
Location
Sioux Falls, SD
TDI
I'm all out...
So is the one 12 x 12 sheet enough to do both doors? Not really sure what the door sizes are.
I know the 2" wide stuff I used wasn't easy to get in the right place, so I imagine a piece the exact size of the door might be a bigger task.

While it might be large enough to do one side of both doors, I would certainly have more on hand. When you stick it to the door, aren't happy with the position, pull the piece off, you're not going to be sure about the condition of the adhesive. I know I threw away about twice as much insulation as I actually stuck to the doors. Stick it to the door, not happy, pull it off, throw it away. I'm not taking it apart again :D and don't want to question the adhesive.

Also, for the price of the stuff listed from McMaster, you can buy the roll from Menards for far less. Additionally, the roll is 720 sq-in vs 144 sq-in. You can screw up a LOT and still have plenty left-over to fix all the rattling panels ;)
 

Jesse_Boyer

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I'm all out...
I was hoping for some quicker :(
This is the quicker, see Post#1.
Yeup, pulling the dash will take an extra 90-120 (estimated) by the time you pull the wheel, steering column mounts, etc. You'll have better access to the doors this way, but its still not entertaining. If you'd like to spend WAY more time, you'd pull the HVAC box itself, split, and do the work on the bench.
 

WAKeele

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Jan 2, 2008
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Missoula, Montana
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2002 Jetta GLS
So I take it my current Jetta is well past the point of blowing foam -- my last one I got a little bit of it in the early stages of third-hand ownership -- so while I'd welcome better temps on both ends, my problem looks to lie in an inoperative blend door.

One morning about two weeks ago now, as the car warmed up to normal operating temp, so did the air coming out of my vents (as usual). I turned the temp control all the way to cold (even though the fan was never on to start with). This did absolutely nothing. Even turned on the AC, but still really hot air. Figured it was the thermostat stuck closed. Replaced it with a new one since they are pretty darn cheap. Didn't help a lick. So I'm guessing the it's the blend door? Anybody with experience with this situation? Would this potentially be enough to solve the problem, or would there be more I may need: http://www.amazon.com/Valeo-509573-Actuator/dp/B001D23ZMY/ I can't have my car down for more than the weekend, so I'll need everything on hand when I decide to tare into things.

And of course I'm going to try this fix while I'm in there.
 

Jesse_Boyer

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Sioux Falls, SD
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I'm all out...
WAK,

Before you assume its the solely foam related, make sure your temperature lever arm is properly rotating the doors. These fail from time to time and it causes the temps to behave like you're experiencing.

Watch this:
https://www.youtube.com/watch?v=6U9ZdkAjdhQ
Does yours behave similarly? If its spreading apart like the video shows, its likely not turning the doors like it should. If so, report back and I'll give you a little shortcut on fixing this... :)
 

supton

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May 25, 2004
Location
Central NH (USA)
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'04 Jetta Wagon GLS
I concur, the arm that moves the blend door likes to fall off on mine. I removed the console to make it easier to snap back in (but it's still a real pain). Do not be fooled by the temperature knob: when the arm falls down, the knob feels exactly the same. The same amount drag etc.

IIRC you can acess the arm by removing a small kickpanel on the driver side footwell, and you can stick your hand up there to find it--it helps to feel around while rotating the temp knob. The Bentley is kinda helpful here also, in letting you know where it is and how to get to it.
 
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