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This is a new-to-me 90 wagon so I don't how things are supposed to function or when they last did. Nothing was working for me: no lights on HVAC control, no fan (not even on "4"). Checked fuses to be sure and then went to it. Sure enough, nearly all of the soldered joints on the harness socket posts had concentric cracks. Touch of iron and solder to each post and I was back in business with lights and all 4 blower speeds. Tried to add a little to this thread with some images of the cracks:

Hmm, maybe this is what happened to my fan "4" setting. I let the car sit for a few months and started it up and now my highest fan setting doesn't work. Really makes you appreciate that high setting once you're stuck with "3".

Thanks for the additional pictures!

I'm glad this thread has helped everyone so much. I remember getting frustrated and hitting the dash when I had this problem over 10 years ago!

Well I finally got around to doing this today, since the 91 hasn't been my DD in a while... My controller was a one-piece board, not two like yours Josh. I reflowed literally EVERY solder joint. Plugged it back in and... Nothing. I can hear the flapper motors functioning as they should (as before the fix).

So the flapper motors are moving? Have you looked at the levers on the vent box under the driver's footwell? Do they move when the buttons are pressed? Maybe one of the actuator arms came off of it's post.

Legacy777 wrote:So the flapper motors are moving? Have you looked at the levers on the vent box under the driver's footwell? Do they move when the buttons are pressed? Maybe one of the actuator arms came off of it's post.

All function as normal. My hvac fan doesn't come on, ever. Before the hvac fans stopped working, the controls would only turn on the fans in position 1 and 4. I was hoping that by resoldering the controls that would fix the issue, but that wasn't the case.

So your problem is with the fan, not necessarily the flapper doors that direct the air?

Have you tried directly powering the fan to see if it works properly?

Legacy777 wrote:So your problem is with the fan, not necessarily the flapper doors that direct the air?

Have you tried directly powering the fan to see if it works properly?

That's the next step I guess.

You have bad resistors in the fan switch. That's why it only worked on setting 1 & 4.

I'm not sure how easy it is to replace those resistors but I know that's what's wrong with my wife's van, fan setting 5 does not work.

I do know that they're supposed to be on the fan box itself behind the glove box.

Good luck.

The resistor pack is easy to replace. Two screws for the glove box, remove an electrical connector, and another two screws for the resistor pack.

First off, YOU ALL ARE AWESOME.

I have a 1990 Subaru Legacy which has had HVAC button issues for awhile. The buttons often won't turn on the air, and if they do it usually reverts to the defroster/sometimes VENT. So from reading through this thread, I may have some solder issues.

Beyond that though, it always seems to work if I tap on the dash, but tonight I tapped a bit too hard and the HVAC buttons are now stuck/smashed into the control panel. Oops.

Will I be able to pop them out if I try to remove the control panel? Is it possible I just have a loose connection thata could be easily fixed? Hard to say, I know.

Apologies if some of the answers are contained within the previous posts, its very late and my focus is waning!

Welcome to the BBS!

More than likely you have similar solder issues on the circuit board. I'm not sure about the buttons whether you'll be able to pop them out or not. Maybe someone else can chime in.

Legacy777 wrote:The resistor pack is easy to replace. Two screws for the glove box, remove an electrical connector, and another two screws for the resistor pack.

It's a vicious cycle if you don't address the original issue. The resistor is an open element type and it depends on the airflow in the box to cool itself. If the fan is dragging, it increases the current and at the same time reducing air flow.

91Beater wrote:It's a vicious cycle if you don't address the original issue. The resistor is an open element type and it depends on the airflow in the box to cool itself. If the fan is dragging, it increases the current and at the same time reducing air flow.

That is a very good point!

JuhaKankkunen wrote:

Richard wrote:My 93 had a similar problem with the hvac too. I couldn't change where the heat/ac went. I did the "piano" method and it seemed to free up for me. But when it was in the off position, I'd hear a wierd sound, like a steady "tip tip tip tip" sound coming from the dash. It happened only once in a while. I'd just turn it on vent and it would go away. My 94 hasn't has that problem yet (knock on wood).

I have a similar problem, today i was looking for about one hour, and i found that the problem was the actuator motor, because the levers in one position doesn't work as free as i think they have to work, so the motor is working in a "hard condition". Tomorrow i will try to lubricate the levers and see what hapen.

.............very difficult for me to explain in english. I have to practice with someone bye MSN.

I've got this problem in my 91. Randomly, a very poor DJ will start spinning his tunes and the noise is quite annoying. Haven't had the button issues (except when cold, the defrost doesn't want to stay depressed), but just the squeaking and the occasional disobedience from the air flow door. I've got some time this evening, so I think that'll be on the menu.

So I am not sure if my problem is related to the one previously posted in this thread, but I figured I would describe what I have going on and see what you guys think.

My HVAC has been working intermittently.
It first stopped working when I was running the AC while stuck in stop and go traffic on the highway.
The AC was blowing strong and cold and then it just stopped. I tried turning it off and on, nothing. Even changing it to other setting seemed to have no effect.

I played with it and after waiting for a short while with it off I could get it to come back on again. I can't really confirm it, but it seemed to want to come on more easily when I moved the temp from cold to hot.

Is this a blower resistor, the solder needing to be redone on the control unit, or is my AC compressor on it's last leg or something?

As always THANKS!

Brisky I would have to say you problem sounds like it's a bad solder connection. When I had to solder my unit the lights would come on for the setting but the fan wouldn't come on unless I hit it hard enough for the bad connection to touch.

If a resistor is bad the fan wont work on 1 or more settings.

FundamentalyConfused wrote:Brisky I would have to say you problem sounds like it's a bad solder connection. When I had to solder my unit the lights would come on for the setting but the fan wouldn't come on unless I hit it hard enough for the bad connection to touch.

If a resistor is bad the fan wont work on 1 or more settings.

Alright. I will have to give that a try.

Thanks!

If it's only the A/C that is not working correctly I would check the joints, but if the A/C randomly goes off and on I would suspect the thermo switch.

Hey there, New to this board and was looking for other information. Stumbled across this thread.

Had the same on again / off again problem with my A/C controls. Took it to the A/C specialist here in town and was told that a new controller was needed. 600 smackers for just the part. Hmm. As the specialist was getting smaller in my rear view mirror, I started to think about it. The biggest stress a hi-way car faces is cyclic loading (vibration). The electronic A/C controller is full of solder. A big component of solder is lead; lead crystalizes under vibration; crystalized substances crack easily. Took the controller out and brought it over to my Stereo Repair Guy. Asked him what he thought. Looking in the magnifying glass, he said, "you have a couple of cracks in your solder." I asked, "can you fix it?" He said, "I can re-solder the whole thing for $20.00." I said, "you can't even buy dinner for $20.00," and gave him $40.

The A/C and the Controller work flawlessly, and has for the last 80,000 miles.

Welcome to the BBS!

Yup, this is unfortunately a common failure point on these cars, but thankfully a relatively easy and inexpensive fix.

I have 1990 sedan and I can't figure out my heater issue.

The heater fan will not work when you initially fire up the car, but if I let it idle or just let the car sit in the garage with the key in the ON position, after 10 or 15 minutes it will turn on. Once it starts working the HVAC unit works great, fan settings 1-4 all work, every button lights up and will change where it blows the air like it should.

I've already taken the HVAC unit out and soldered up all the connections. The fan motor works good. It doesn't seem to be a bad ground or anything because it will eventually turn on without an movement.

Any ideas on where to check next?

Welcome to the BBS.

Is it just the heater fan that will not work? Do you hear the mode door selector moving when selecting the different buttons?

If it's just the motor, you may want to check out this thread.

http://bbs.legacycentral.org/viewtopic.php?f=19&t=55198