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'92 Legacy Wagon - Heater select switch not working.


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13 replies to this topic

#1 OldeSeoul

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Posted 26 December 2006 - 08:48 PM

Hi All..

First post here. Any help would be appreciated.

Our '92 Legacy Wagon is a trooper, 260,000 miles and still doin' okay... but our most recent challenge is the heater/blower/area selector...well, that's the official name ;-)... I call it the (pushbutton) control that selects where the heater blows - Defrost (windshield), Heat (comes out at feet), Bi-Level (comes out at feet and through centrally located main vents).

Recently, the air started to blow out the centrally located main vents ONLY. When the symptoms first started, it briefly started to WORK again...blowing air through the defrost vents... but that ended within a day. The dying gasps of whatever was going bad, I guess. Now it only blows out the main vents.

Finally, now that the hot air will only come out the main vents (all fan speeds work fine...so it's not my resistors)... the air comes out the passenger side a lot stronger than it does on the driver's side... but even the drivers side has SOMEthing, as opposed to the Heat and Defrost vents which pass little air if any (the windshield defrosts over about 20 minutes...so there must be some SLIGHT air getting there - probably just peripheral currents).

Okay... so now my question.

Is it more likely that this is a problem with the electronic push button dash control unit... or with some sort of linkage that controls where the air blows?

If it's the former, I'm assuming I'll have to remove the push button heater control unit on the dash and see if I can repair. If it's the latter, I'm hoping I can access the flow tubes or directional gates from under the dash.

Totally willing to get my Novice hands dirty, just need to get some guidance on where to start.

Thanks in advance for any suggestions or tips.

...Jeff

#2 DaveT

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Posted 26 December 2006 - 09:33 PM

Is it more likely that this is a problem with the electronic push button dash control unit... or with some sort of linkage that controls where the air blows?


The buttons control air valves that rout vacuum or not to various diaphragms that move flaps that rout the air.

There is 1 "main feeder" vacuume line to the selector - I think it should be on the passenger side under the hood near the firewall. check that it is connected / not leaking / etc. first.

#3 Manarius

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Posted 27 December 2006 - 01:11 AM

I wonder if the blower door actuator is sticky. I don't know exactly where it is, but if you look at the bottom of the center of the console, there should be some place where a lever is exposed. This lever controls airflow and sometimes it can get stuck.

#4 nipper

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Posted 27 December 2006 - 02:09 AM

How does the car run? is it running a lttle rough?

The HVAC controller is a bunch of vacume operated switches, which is fed from a resivoir. If nothing at all is working either the HVAC control went bad, or there is no vac to control.


nipper

#5 ericem

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Posted 27 December 2006 - 02:17 AM

Well i think this is a simple issue, when i was expirementing behind my glove box, i unpluged a connector attached to the heater core of course, and on heat mode it wouldn't work but all other modes work, then when i plugged it back in heat worked. Its on the passenger side, behind the glove box. Good luck.

#6 OldeSeoul

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Posted 27 December 2006 - 10:39 AM

Thanks, everyone, for your suggestions.

When it gets light outside, I'll get out there to have a look. Because of all your comments, at least now I have an idea of what I'm looking for.

I'm hoping it's a simple matter of a disconnected plug like EricEM suggests...I DID recently have something drop out the back of the glovebox and it was a BEAR getting it out - would've been real easy to tweak something without knowing it.

Also, I'll look in my repair manual to see if it shows where the blower door actuator is....that sounds highly suspect as well. It'd be great if all I have to do is smack it heartily to get it unstuck and working again.

I'll repost what I find out. Thanks again!
...jd


...and to answer Nipper -

The car runs pretty good for the mileage it has on it, but it's kind of loud (embarrasses the hell out of my girlfriend's son ;-) but *I* don't think it's really THAT loud). It sometimes gets something akin to a vapor lock going at high speeds up a hill (like getting onto the freeway) - pulling over, the car chugs and dies, but after a second of waiting, I restart and we're fine. If the vac system weren't working, I'm pretty sure the car would be running noticeably worse that it does.... but just in case this is related to the reason the heater is acting up, I *will* definitely check the vac system .. per your suggestion. Thanks again.

#7 ericem

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Posted 27 December 2006 - 11:42 AM

Thanks, everyone, for your suggestions.

When it gets light outside, I'll get out there to have a look. Because of all your comments, at least now I have an idea of what I'm looking for.

I'm hoping it's a simple matter of a disconnected plug like EricEM suggests...I DID recently have something drop out the back of the glovebox and it was a BEAR getting it out - would've been real easy to tweak something without knowing it.

Also, I'll look in my repair manual to see if it shows where the blower door actuator is....that sounds highly suspect as well. It'd be great if all I have to do is smack it heartily to get it unstuck and working again.

I'll repost what I find out. Thanks again!
...jd


...and to answer Nipper -

The car runs pretty good for the mileage it has on it, but it's kind of loud (embarrasses the hell out of my girlfriend's son ;-) but *I* don't think it's really THAT loud). It sometimes gets something akin to a vapor lock going at high speeds up a hill (like getting onto the freeway) - pulling over, the car chugs and dies, but after a second of waiting, I restart and we're fine. If the vac system weren't working, I'm pretty sure the car would be running noticeably worse that it does.... but just in case this is related to the reason the heater is acting up, I *will* definitely check the vac system .. per your suggestion. Thanks again.


Loud eh? Do you mean the engine is loud? or the exhaust:-p Just because it has high mileage doesn't mean it will run rough, ill tell you what, these cars could probably run like day one for ever. Do you get a check engine light?

l

#8 Legacy777

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Posted 27 December 2006 - 12:27 PM

I really don't believe the HVAC system on the legacies is vacuum actuated. I'm pretty sure they use stepper motors.

More then likely the solder joints in the HVAC unit are cracked. You can take the unit apart and resolder them. Check out the HVAC sticky in the body & chassis forum on www.bbs.legacycentral.org

#9 montana105

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Posted 27 December 2006 - 06:50 PM

I'm leaning towards vacuum because I know in my 93 Wagon L when climbing mountainous grades the defrost shuts off and blows cold air out at my feet,this only seems to happen near or at WOT. It's never bothered me enough to tear apart anything.
John

#10 OldeSeoul

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Posted 28 December 2006 - 12:24 AM

Loud eh? Do you mean the engine is loud? or the exhaust:-p Just because it has high mileage doesn't mean it will run rough, ill tell you what, these cars could probably run like day one for ever. Do you get a check engine light?

l

Every once in a while...usually soon after starting the car for the day... we'll get a check engine light, but it goes off after less than a minute - at least it has so far (knock on wood). As far as what's "loud", I'm guessing my girlfriend's son is referring to the engine. Personally, I don't see it...I mean, it's not stealth like a new car, but a little clacking and vroom from the running engine is pretty standard for an older car. For a car with its mileage, it really runs pretty smoothly...but just like me, when you get older - you tend to make a few more noises. I'm very happy with it, but it IS getting old. I'm thinking this heater problem is just another symptom of the age gremlins. <I've posted below regarding my progress>

#11 OldeSeoul

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Posted 28 December 2006 - 12:38 AM

I really don't believe the HVAC system on the legacies is vacuum actuated. I'm pretty sure they use stepper motors.

More then likely the solder joints in the HVAC unit are cracked. You can take the unit apart and resolder them. Check out the HVAC sticky in the body & chassis forum on www.bbs.legacycentral.org

Thanks for the URL reference... what a great resource for Legacy owners. In fact...the thread you referred me to sounds EXACTLY like the problem I'm having. I have high hopes for my efforts tomorrow.

To Everyone - I appreciate all of your suggestions. Just an update/response -

The heat factor hasn't been an issue, that is, the air that blows gets warm like it should. The problem is that it only blows out the mid-level vents (not "Heat", which comes out at your feet, nor "Defrost" which comes out at the windshield...or any combination involving either).

I poked around behind the glove box, but didn't see any loose connections. I couldn't really see behind the dash control unit, but maybe if I remove the center piece (ashtray and cubby hole), it will give me access. The website Legacy777 referred me to has some great suggestions, too. I'll keep ya'll informed. - I plan to be upside-down in my front seat for a while tomorrow.

Meanwhile, Thanks all for your ideas. I've read each comment and will go down the list as I troubleshoot. It sure helps to have this kind of forum and have people willing to spend time helping others. Thanks again.

What an age...the Internet sure has changed the way we get info. I like the synergy a "Hive" can offer. Hopefully, I'll be able to help someone else down the road to keep the love flowing... ;-)... :headbang:
..jd

#12 nipper

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Posted 28 December 2006 - 12:46 AM

I really don't believe the HVAC system on the legacies is vacuum actuated. I'm pretty sure they use stepper motors.

More then likely the solder joints in the HVAC unit are cracked. You can take the unit apart and resolder them. Check out the HVAC sticky in the body & chassis forum on www.bbs.legacycentral.org


Your right i just double checked, its all electric. This actually makes it easier to diagnose.

nipper

#13 ericem

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Posted 28 December 2006 - 02:09 AM

Every once in a while...usually soon after starting the car for the day... we'll get a check engine light, but it goes off after less than a minute - at least it has so far (knock on wood). As far as what's "loud", I'm guessing my girlfriend's son is referring to the engine. Personally, I don't see it...I mean, it's not stealth like a new car, but a little clacking and vroom from the running engine is pretty standard for an older car. For a car with its mileage, it really runs pretty smoothly...but just like me, when you get older - you tend to make a few more noises. I'm very happy with it, but it IS getting old. I'm thinking this heater problem is just another symptom of the age gremlins. <I've posted below regarding my progress>


only comes on sometime eh? Had the same symptom when i need a new CAT, and O2 sesnor. If it runs fine for you leave it, hopefully it passes inspection though(emission wise).

When u removed ur glove box(if you did) did u see a plug going into the heat core, like it was going into a small(what the heck can i call it) It was plugged into a while plastic board? When i unplug that i dont have heat anymore. But all it looked like after i removed it was a thermostat:-\(that was rusted heavily. guess moisture builds in there).

#14 Legacy777

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Posted 28 December 2006 - 10:42 AM

Every once in a while...usually soon after starting the car for the day... we'll get a check engine light, but it goes off after less than a minute - at least it has so far (knock on wood). As far as what's "loud", I'm guessing my girlfriend's son is referring to the engine. Personally, I don't see it...I mean, it's not stealth like a new car, but a little clacking and vroom from the running engine is pretty standard for an older car. For a car with its mileage, it really runs pretty smoothly...but just like me, when you get older - you tend to make a few more noises. I'm very happy with it, but it IS getting old. I'm thinking this heater problem is just another symptom of the age gremlins. <I've posted below regarding my progress>


If the check engine light has come on at any point, it should store a code. Check the ECU for stored codes. The procedure can be found on my site along with the codes

www.surrealmirage.com/subaru/engine.html

Also, to get at the HVAC unit, you have to remove the black plastic surround trim. To get that out, you need to pull the vents, cruise/heater buttons, and the air susp. blank out to get at the screws behind them. You'll also need to loosen/remove the two bolts holding the steering column to the dash. That will lower the steering column enough so you can wiggle the black plastic piece out.

Once that is out, you can get at the HVAC unit. The plugs are a little bit of a pain to get at, but once you get it out, you should be able to look at the solder joints for cracks. There's some pictures I posted in that thread on the bbs.




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