1999 Outback Stuck on Defrost

[Johnny Subaru]

Hi there, trying to diagnose this problem. 2.5L 1999 Outback Wagon

Air temperature is fine--its hot when set to heat and AC works, everything just blows out of defrost only. I pulled the vents off the center console to reveal the blend/mode door and it does not move when I change setting from feet to vent, etc. I even gently push on it and it is stuck closed pretty solid. 

I did some digging around and a lot of people are saying it could be a vacuum line. I hear a lot of vehicles around this time were made with pneumatically actuated mode doors. I haven't seen any obvious lines that are disconnected or broken. Perhaps someone could direct me to exactly which lines I should be looking at for this?

Im hoping the problem is just a simple vacuum line, but in the case that it is the vent mode actuator, does anyone know where that is located on this model?

I also confirmed the issue is not the EGR solenoid. I know that may seem unrelated, but I saw a video of a guy with a Ford having this problem, and he replaced that solenoid and solved the problem. I tested mine and it works. 

Thanks for your time!

[jonathan909]

I have the same problem with the same model/year, only it's simply "reluctant" to move the door rather than absolutely stuck.  So during the winter, once we get it to move to defrost+floor, I tell everyone just to stay the hell away from the control and don't ask for trouble.  Why haven't I fixed it?  Because I'd rather do three HG jobs and pull a Mustang motor for a timing kit (like I did this summer) than crawl under (or take apart) a dash once.  But I know I'm going to have to deal with it sometime - probably this spring.

Poking around online recently, though, I found discussions of the problem actually being with the control head PCB.  Apparently (as with the instrument cluster) pulling it out and just reflowing (resoldering) all the joints generally solves the problem, so I plan to start there.

Edited December 3, 2022 by jonathan909

[idosubaru]

The units themselves are prone to fail.  A 99 Outback is going to be like 95-98 legacy outback’s and there’s a metal rod connecting the control unit to the blend door. I’ve seen them simply get disconnected down above the passengers side feet. It’s been a few years since I did one so I don’t recall specifics but look up there and it should be obvious if it’s connecting and working properly. I’d look there first then assume the control unit is bad. 

Not sure what the vacuum contraption would be on a 1999, was that 99 Outback info you saw on rhay?

[lmdew]

The temp control is a cable that routes down to the passenger side of the center counsel.  you can look up and see it move as you slide the temp lever.

The vent control is electrical, push button control.  Yes, sometimes it's the board in the controller that fails.  You can change out the board.

It goes down to an actuator on the drivers side of the center counsel.  Pull the lower kick panel and then crawl up under there and you will see the linkage.  I've had the linkage fail, the actuator or the control board.  You Pull and Pay yards are your friends.  Poke around there first is always a good idea.

[Johnny Subaru]

Thanks all, I will check out these leads and report back. 

[lmdew]

Happy to meet you at the Laurelwood Public house if you need help.  Just a couple hour flight out from Colorado.  Great fish tacos and Workhorse IPA.  I was just there last week.

[Johnny Subaru]

Alright, another possibility ruled out. I have another '95 Legacy so I pulled the climate control unit off that and plugged into this '99 and no luck. All the buttons light up, so it's getting power, but it does not move that mode door. I also don't hear any noises like clicking or or grinding or anything like that. 

If I am understanding this correctly, there is a linkage mechanism that moves the mode door, which is connected to the actuator correct? I'm guessing since I am not hearing any movement or grinding or clicking, the actuator itself may be bad. If the actuator was functioning it would at least attempt to move the linkage and make noise. 

idosubaru to answer your question from above, no it wasn't a Subaru. It was a video on a 2003 GMC Safari which has vacuum actuated mode doors. Here's the video link if you are curious: https://www.youtube.com/watch?v=wcZNtRsD4jI 

lmdew - if i really get stuck I've got a guy at my church that can help me out, but I think I can probably figure this one out a step at a time. I'm a novice, but I like to learn. 

[Johnny Subaru]

I finally pulled the actuator and figured out how to test it. Last 2 pins on the far right. It does move with power, so that must mean it's good right? 

Im thinking its the linkage now. I'll probably have to get to it Monday. 

Edited December 4, 2022 by Johnny Subaru

[jonathan909]

When powered from what?  The controller, or on the bench?

[Johnny Subaru]

On the bench. Car battery. 

[jonathan909]

So problem in linkage or controller.

[lmdew]

If the linkage/doors are moving freely, the board in the controller is most likely the cause.  I've swapped out many of the boards over the years.  Just take your time.

[Johnny Subaru]

Imdew - what do you mean by the board in the controller? Is that just the climate control panel? 

If so, see my post above. I already tested a working controller in this car from my 1995 and it did not actuate that mode door. Does that make sense? Since the working controller did not actuate the door, that suggests to me the problem lies elsewhere.. 

[Ferret54]

There are 2 parts to that actuator. The motor that moves the door, and a variable resistor to feed back how open the acutator is. Since you tried another panel ( controller ) and the motor moves when you apply power, then I would still replace the actuator as I suspect the variable resistor inside is defective. It's simply a slider on a carbon path that does wear out over time.

 

Replaced many of these on all different makes of vehicles. They all seem to work the same, just with different controllers or panels.

Edited December 5, 2022 by Ferret54
spelling

[lmdew]

I'm not sure that the 95 and 99 controlers are not exactly the same.  Yes the board is part of the control panel.  You can replace just the borad.  It's not hard, you just have to take your time.  Small plastic lock tabs hold it in.

[Johnny Subaru]

Alright, so it looks like Subaru discontinued this part so I am unable to order it. My local junk yard also does not have any Subaru's from 1995-1999 which all use the same mode door actuator. I decided to do what several others have suggested, just manually move the linkage to set the mode door to defrost/floor for the winter and then move it to vent for the summer.

I did find one guy on youtube parting out a 1997, so I contacted him about an actuator. Other than that, we will see if I can track one down. I'll post here with any updates that would be helpful for the community.  

Thanks all for your time and knowledge, I appreciate the help. 

Johnny 

[jonathan909]

Does that mean you've ruled out the controller as the possible source of the problem?

[lmdew]

www.car-part.com

eBay?

I'm sure I could find one here in Colorado.

[Johnny Subaru]

jonathan99 - I did swap my working controller from my '95 and it didn't actuate on the '99. 1995-1999 Legacy's (and Outbacks) have a lot of overlapping parts. I did something similar to diagnose a bad temp gauge in my '95 - swapped the dash clusters with the '99 and it worked. So I guess it's not 100% guaranteed that the problem doesn't lie in the controller. Is there another way to test this? I guess I could put this controller from the '99 into my '95 and see if it works? But Imdew mentioned these controllers may not be the same. 

Imdew - I looked on Ebay, Autozone, Rock Auto. Subaru.com says they discontinued the part. Car-part seems cool, but a little tough to use - like I can't search for a specific part or enter a part number. Speaking of which, this part number for the actuator is: 72143AC010

[heartless]

for the control unit...  https://www.car-part.com/cgi-bin/search.cgi

car-part is not that difficult, really.. chose year, model, the part you are looking for (sometimes need to get creative, or chose something related) chose sort settings and area, click 'search' - it may ask for more info on the next screen, select the appropriate option, search again.. then go thru the listings..

if the exact part you are looking for - in this case, the actuator - is not listed.. use something related, like the control unit, then contact listed yards and ask about the actuator.

[jonathan909]

On 12/7/2022 at 10:23 AM, Johnny Subaru said:

jonathan99 - I did swap my working controller from my '95 and it didn't actuate on the '99. 1995-1999 Legacy's (and Outbacks) have a lot of overlapping parts. I did something similar to diagnose a bad temp gauge in my '95 - swapped the dash clusters with the '99 and it worked. So I guess it's not 100% guaranteed that the problem doesn't lie in the controller. Is there another way to test this? I guess I could put this controller from the '99 into my '95 and see if it works? But Imdew mentioned these controllers may not be the same.

Yeah, that means that you'd get another data point, but it may not be definitive.  The best test is the one you did, but the negative result could mean the problem is somewhere else (i.e. the actuator) or the two controllers are different.  I would think a simple visual check (including comparing part numbers, if any) would answer the latter question; if they're different, trying the '99 in the '95 probably isn't going to work either.  But don't forget what I mentioned previously - that others have reported simply reflowing (resoldering) all of the joints on the controller PCB and had it spring back to life.  I haven't done one yet, but it's small and will only take a few minutes, so it doesn't make sense to me not to try.

[lmdew]

I think I have a controller or two at home.  I'm out till the 19th.

[Stevo F]

I had 3 late 90's Legacy's and all had issues with the HVAC control units. I tried used units and they'd work for a short time, then the buttons to change the flow would no longer respond (it would usually get stuck coming through the dash only no matter what buttons I pushes). I believe it was a design flaw with the system board that the cable plugs into. The only triue fix I found was buying a new OEM HVAC unit (they can be had for around $200+ online). After that, both new units worked well until we got rid of the cars.