1996 850 Wagon ECC damper door stuck

[Jazzer]

Hi guys,

first post here; thought I'd wait until I got stumped to put out a question, and it only took me a month since I picked up a Platinum edition 96 850 Estate, 170k. Needs a little TLC, but I'm slowly nursing it back to health. I really like the feeling that I can fix pretty much anything on this car if I turn to these forums, very cool.

I've read a lot on the ECC stuck damper door, and I've got the usual problems: vents are stuck on the defrost position, though I still have a little bit of air blowing through the upper and lower vents. It's not terrible, at least not until winter when I'll need the heat on the feet. I've also got the split "spline" that the motor turns to open the damper. From what I've read, it sounds like you should be able to turn this door by hand? For me this door is stuck closed, like really stuck. I can't move it by hand or by reaching up through the floor vent opening and pushing on it. I don't want to break it so I'm not going to force it.

Checked the motor with the 9volt battery trick; it worked fine. However, when I ran the center ECC knob through its paces (auto, upper vents, lower vents, etc.), the motor did NOT move (it was plugged in but detached from the door). Does this sound like a bad ECC unit to anyone? If so, I guess I've got a bad ECC unit (an easy swap) plus a stuck damper door (not an easy fix, I'm thinking). Please let me know what you think!

Thanks,

Bob near Pittsburgh

[scot850]

I had a similar problem with a 93 850 with ECC. The main flap on the LH side actually melted its rubber edge seal and stuck to the inner side of the unit. You can't buy the flap separately fro Volvo so you have to pull one from a parts car which means pulling the whole dash and steering wheel/airbags out. Then pull the heater system out, split it down to open it up and replace the flap with hopefully a better one.

The other problem they have is that the end of the shaft is a plastic square recess, and when the motor tries to turn the stuck flap it cracks the end of the shaft and so the motor works, but the shaft doesn't move. You can buy and replace that part without removing the dash. Some guys have used a small hose clamp around the shaft to fix it.

Neil.

[Jazzer]

Thanks for that info; I figure it may be something like that. Of course it's something that will require tearing the dash apart, but it may be a nice fall project...

I do have the broken shaft as well; I've seen some inventive fixes for it. I like the small hose clamp idea, though if the door flap is stuck then it won't do me any good until i get that moving. Not sure if the motor is 100% or not; it worked when I took it out and tested it, but when I tried it in the car it didn't move at all. Not a huge problem now, since my AC is working nicely, but in the fall it will need fixed.

Bob

[scot850]

Motor may have failed due to over work!

There is a good write up on MVS for replacing the A/C evaporator with loads of pictures. It was a life saver! Bless all the good folks who take the time to write stuff up for us!!

Neil.

[Jazzer]

I'll be sure to check it out, thanks!

Bob

[clarkr]

Hi All,

1996 Volvo 850 Turbo Wagon - ECC type electronic heating cooling system. Not sure if the same on the manual type controls.

I know this is a really old thread but I thought I might offer some options on stuck flapper doors on the floor and defrost flaps being stuck in the down position with no heat on the floor. This is for anybody searching for some help. There is a thin rubber seal around the flap doors that I guess melts to the plastic. This is the stuck flap door.

First I pulled the lower molding panel off under the dash, removed the glove box, and unscrewed the damper motor that connects to the floor/defrost flaps. It was a real pain in the butt getting the lower T15 screw out on the bottom right. I couldn't get a torx screw driver to line up and the space was too small for a torx socket. I ended up buying a set of torx keys (come in a pack like the allen keys with long shafts and a 90 on the other. I used the long shaft to unscrew the torx screw and it came off easy. Be sure you put a paper towel underneath so you don't lose the screw down below.

Once the motor was off I tried to turn the shaft that the motor was inserted into that moves the flaps up and down by hand. Just my luck, it wouldn't budge. This stuck flap also caused the motor to break the shaft like many have had happen and is documented elsewhere. I repaired this after getting the flaps to move again.

I certainly didn't want to remove the entire dash to try and fix the problem with the stuck flaps so I tried this method:

Where the air comes out on the floor on the bottom of the dash there are two channels that air flows down passenger side and drivers side. You can look up these channels with a flashlight. The shaft is at a slight angle and the black flapper door will be on the right hand side (passengers channel). I took a sturdy wooden dowel cut to length to fit up the channel and lined it up on the flap. I pushed hard until the flap came loose. In mine the flap on passengers side was the one stuck and not both. If both are stuck I believe you could do the same on the drivers side I would assume or visa versa.

Once this popped loose I could then turn the shaft by hand easily. Problem solved on not getting heat on the floor during the winter. Reinstalled the motor on the repaired shaft and put everything back together.

Hope this helps someone with cold feet in the winter.

NOTE: it was below freezing when I did this. I put a small electric heater in the rear of the wagon to warm temps up enough for glue to dry and let it sit for 24 hrs.

[Clemens]

Thank you for the writeup. Photos would have been a bonus, but below freezing are not the conditions to grab a phone with frozen fingers while trying to restore heating.

I think deteriorating foam around the flaps and too little usage are the combination to get the flaps stuck. These are the problems we encounter because these p80s just run longer than most engineers plan for

[abscate]

Is there a preferred position to leave the flaps, perhaps both mid and floor distribution, thst would prevent the foam from sticking and causing this problem ?

[scot850]

The flaps go gooey over time and eventually can stick as you have found. I ended up replacing the flap while in replacing the evaporator.
Un-sticking it will only be temporary.

Neil.

[clarkr]

Thank you for the writeup. Photos would have been a bonus, but below freezing are not the conditions to grab a phone with frozen fingers while trying to restore heating.

I think deteriorating foam around the flaps and too little usage are the combination to get the flaps stuck. These are the problems we encounter because these p80s just run longer than most engineers plan for

Hi Clemens,

It appears that these flap/doors have a black rubber affixed to the outside edge of a hard plastic door that seals the chamber off at the floor vent to prevent air reaching the floor. I am assuming that heat and deterioration of the rubber is the cause of the sticking. I don't know if this will cause a sticking problem in the future as scott850 mentioned below but at least it has temporarily worked for me. I have heat on the floor now. If I have a little blow bye because it is not sealing all the way is just fine by me winter or summer.

I have thought about a process to try if it becomes a problem again. It might take some ingenuity but I thought if you sprayed an aerosol silicone spray up into the floor vent that it is open and then when it is closed might, I say might, make the rubber at least not as sticky as before. Someone with an idea how to hook a small diameter hose about 12" long to a spray can and shove it up in the open vent may work? Or maybe if not using an aerosol spray possibly some of the plastic, rubber preservative like for interiors from Maguires sprayed up there may also do the trick.

On the process of fixing the broken shaft on the flapper doors: Mine cracked the end of the plastic shaft. There was one piece that came out away from the fitting. I carefully took some JB Weld superglue and tacked it together being careful that it fit as perfect as possible so there would be no problem shoving the metal motor shaft into it. Let it dry.

With the plastic tacked together I mixed up some JB Weld black two part epoxy and with gloves on smeared it generously around the shaft being careful not to get any where the shaft goes through the hole going into where the flappers are. If the space is too tight you may try using a Q-tip to smear the glue around the shaft. While still wet, I took one of those squeeze spring hose clamps that fit over the shaft tightly (checked before any glue on the plastic) and placed it over the JB black epoxy where the break was while still wet. I then smeared by hand more JB over the entire clamp and shaft by hand to lock this metal support onto it to prevent hopefully it breaking again. Fingers crossed.

Here is a Youtube video of what it actually looks like inside. It is a great piece of information on how it all works: