For those of you who continue to have issues with vents being different temps after replacing the heater valve. I believe I found your problem.
I have gone through the heater boxes for 04, 05, and now 09 cars. Stepper motors RARELY go bad, it's usually a linkage that is the issue.
Then there is the pic I included. Some of the blend doors or flaps have a rubber seal/coating around and over them. This melts over time from the temp of the heater core and heat/cool cycles. It turns in to RTV almost. Then the flaps get sticky and cause gaps and holes as you can see in my photo. I also included a pic of what it SHOULD look like.
I've been on a mission since installing the killer chiller. Even though the killer chiller affects cabin temps, having these huge gaps and holes will make a factory system without a killer chiller seem horrible.

I have finally dug into my heater box. The job its self is not too bad, just very timing consuming. You DO NOT have to evac the ac or anything. The boxes are designed to come apart. It is easier if you can extract then pull the whole assembly out.

Video of assembly -
Photo breakdown:
1. is an example of a bad heater box. Left is the passenger side, right is the driver side.
2. is a good heater box I got from an 09 car.
3. is how the blend doors come out as an assembly.
4 - 6. - is some break down shots of the dash tear down to get to the heater box.
7. Is my actual heater box that I removed. The driver side top vent was broken, they changed this design in 07 or something. It is one big door instead of being split into 2 vents. The 07+ have less stepper motors as well. I repaired this with parts from the car I parted out. This being broken took pressure away from the front vents and pushed it up to top vents.
8. My front driver vent is all gummied um and passenger is perfect. I swapped this from my parted out car, it was in perfect shape.
9. Boom, all back together and like new, ready to go back in. I even took time to heat up and bend some plastic back in place for the spring loaded blend door in the top part. It will bend and cause it to "skip" then it will throw a code for the stepper motor being out of range.
10. It's back in, clips are on, all stepper motors are in place and plugged in. I even got to clean up wiring from previous owners and old projects.
11. The bone yard.
12. Getting closer to being back together.
13. Even closer.
14. Back together enough for testing. All vents are fixed. ****. Yes. When first started it up, only had the passenger side was blowing air and nothing was coming out the driver side. I was so bummed. I ended up having to hook up to star and then have the system reinitialize the motors. As far as AC, this thing is done. I have some final touches with a new unit before finishing it all up.

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All of that for cold air.

Yes, it was worth it.

 

Nice write up. This should help others In the future.

 

Thanks for the write up T.

 

Nicely done! I always wondered what the inside of the heater box looks like.
I pray that I won't need to remove the dashboard ever. I have a high-end aftermarket sound system and i can only imagine the pain of R&R all the wires.

Cheers.

 

thanks for this ,,,, my top windshield defroster vent on passenger side seems to be stuck open, is there a way to reach down there with a coat hanger and move it(free it up) or do i have to do some major surgery like your pictures show ? -- thanks again

 

Good lord this write-up is nightmare fuel! Glad it worked, and hope like hell I never need to seek the advice you have offered.

 

Yeah I got cold sweats when I saw the steering column dropped...

 

It depends on the year of car. You can remove the a/c control panel and speaker assembly. The top dash is about 10 screws or so and comes out in about 20 minutes maybe 25... You can reach some.

 

Hi, All,

could anybody re-upload or re-link the pictures again? I think I must fix my heater matrix and those pictures would be very useful for me.

Thanks.

 

Here's a link to the vent pictures.

"https://photos.app.*******/KUkG3NngnkuXkUDJ8"

 

Thank you very much.
*******

 

I have a different problem, where my back seat vents are heat all the time. Could this be a similar issue?

 

Yes, those are controlled at the bottom in the hvac box.

 

link to photos is broken; could you resend please?

 

https://photos.app.*******/KUkG3NngnkuXkUDJ8

replace the ******* with goo then .gl. this site is editing it.

 

It's the forums filter

https://shorturl.at/istuR