HVAC controls not working all the time

Anything and Everything about the Body, from paint to undercoating and interior, including in-car entertainment (ICE).

Moderators: Helpinators, Moderators

archerw
In Neutral
Posts: 13
Joined: Sat Feb 09, 2013 9:44 am
Location: Fairbanks, AK

Re: HVAC controls not working all the time

Post by archerw »

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:

Image

Image

Image
kimokalihi
Fifth Gear
Posts: 8360
Joined: Mon Nov 06, 2006 3:41 am
Location: Tenino, WA

Re: HVAC controls not working all the time

Post by kimokalihi »

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".
98 Metro Hatch Daily Driver :)
91 SS EJ20G Engine/Tranny/Diff Swap Build Thread Here
"Your testes are close to your bottom but you still play with them all the time." Jeremy Clarkson
Legacy777
Site Admin
Site Admin
Posts: 27884
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Re: HVAC controls not working all the time

Post by Legacy777 »

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!
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
mike-tracy
Moderator
Moderator
Posts: 5000
Joined: Tue Aug 25, 2009 7:52 am
Location: Des Moines, Wa

Re: HVAC controls not working all the time

Post by mike-tracy »

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). :(
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote: Mon Jan 14, 2002 10:23 am Wait....I'm confused now.
Legacy777
Site Admin
Site Admin
Posts: 27884
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Re: HVAC controls not working all the time

Post by Legacy777 »

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.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
mike-tracy
Moderator
Moderator
Posts: 5000
Joined: Tue Aug 25, 2009 7:52 am
Location: Des Moines, Wa

Re: HVAC controls not working all the time

Post by mike-tracy »

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.
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote: Mon Jan 14, 2002 10:23 am Wait....I'm confused now.
Legacy777
Site Admin
Site Admin
Posts: 27884
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Re: HVAC controls not working all the time

Post by Legacy777 »

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?
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
mike-tracy
Moderator
Moderator
Posts: 5000
Joined: Tue Aug 25, 2009 7:52 am
Location: Des Moines, Wa

Re: HVAC controls not working all the time

Post by mike-tracy »

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.
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote: Mon Jan 14, 2002 10:23 am Wait....I'm confused now.
FundamentalyConfused
First Gear
Posts: 202
Joined: Sat Mar 03, 2012 5:04 pm
Location: Flint, MI

Re: HVAC controls not working all the time

Post by FundamentalyConfused »

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.
1999 Forester S 5MT 200,000 miles and counting.
1990 Legacy L Sedan AWD 5MT Retired at 369,471 Miles
Legacy777
Site Admin
Site Admin
Posts: 27884
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Re: HVAC controls not working all the time

Post by Legacy777 »

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.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
thomassy
In Neutral
Posts: 1
Joined: Sat Mar 29, 2014 8:27 am

Re: HVAC controls not working all the time

Post by thomassy »

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!
Legacy777
Site Admin
Site Admin
Posts: 27884
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Re: HVAC controls not working all the time

Post by Legacy777 »

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.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
91Beater
First Gear
Posts: 219
Joined: Thu Mar 08, 2012 12:37 pm
Location: pdx

Re: HVAC controls not working all the time

Post by 91Beater »

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.
Legacy777
Site Admin
Site Admin
Posts: 27884
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Re: HVAC controls not working all the time

Post by Legacy777 »

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!
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
RoughDiamond
First Gear
Posts: 121
Joined: Fri Dec 19, 2014 8:39 am
Location: Akron, OH

Re:

Post by RoughDiamond »

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. :D
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.
1991 Legacy SS (BC) EJ22T // 4EAT // Pewter Metallic (Sold)
1991 Legacy SS (BC) EJ22T // 5MT // Rio Red (Sold)

1991 Legacy SSRS (BC) EJ20G (Full COP and AWIC Swap) // 5MT // White Pearl Tri-Coat Africa Rally replica in progress.
Brisky
First Gear
Posts: 60
Joined: Sat Jan 28, 2012 8:52 am
Location: Kent, WA

Re: HVAC controls not working all the time

Post by Brisky »

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!
Brian

2001 Legacy GT - Sedan - White - Manual

18inch TSW Wheels, Federal SS-595 Tires, Centriic Rotors, Stoptech Brake Pads, STi Exhaust, & Torque Solutions Shifter bushings
FundamentalyConfused
First Gear
Posts: 202
Joined: Sat Mar 03, 2012 5:04 pm
Location: Flint, MI

Re: HVAC controls not working all the time

Post by FundamentalyConfused »

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.
1999 Forester S 5MT 200,000 miles and counting.
1990 Legacy L Sedan AWD 5MT Retired at 369,471 Miles
Brisky
First Gear
Posts: 60
Joined: Sat Jan 28, 2012 8:52 am
Location: Kent, WA

Re: HVAC controls not working all the time

Post by Brisky »

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!
Brian

2001 Legacy GT - Sedan - White - Manual

18inch TSW Wheels, Federal SS-595 Tires, Centriic Rotors, Stoptech Brake Pads, STi Exhaust, & Torque Solutions Shifter bushings
rallyak
Third Gear
Posts: 896
Joined: Wed Oct 26, 2011 7:02 am
Location: Anchorage,Alaska

Re: HVAC controls not working all the time

Post by rallyak »

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.
Charles

90' White/Gray Outback DD workhorse (670,xxx) miles
92' Onyx Metallic (430,xxx) Wife's DD
68' Barracuda formula S 340 4spd coupe (ongoing project)
66' Mustang 2+2 4spd wife's (ongoing project)
Pleiads
In Neutral
Posts: 1
Joined: Wed Dec 16, 2015 10:28 pm

Re: HVAC controls not working all the time

Post by Pleiads »

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.
Legacy777
Site Admin
Site Admin
Posts: 27884
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Re: HVAC controls not working all the time

Post by Legacy777 »

Welcome to the BBS!

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

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
1stGenSubieLeg
In Neutral
Posts: 2
Joined: Sun Jan 17, 2016 6:21 am

Re: HVAC controls not working all the time

Post by 1stGenSubieLeg »

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?
Legacy777
Site Admin
Site Admin
Posts: 27884
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Re: HVAC controls not working all the time

Post by Legacy777 »

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
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
Post Reply