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Replacing A/C Heater Control Unit


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Need instructions on removing and replacing the A/C control unit on a 1992 Legacy AWD wagon 5-sp. I think everything else has been checked out including jumping the pressure sensors, directly powering the compressor, and checking all fuses and relays. The A/C works intermittantly. I had a shop replace the original control unit with a recycled one recently with no improvement. However, I disassembled the one taken out and found a blown diode in the circuit board. There is a bunch of them in there, just one bad apple! I plan to rebuild one good one from the 2 and reinstall it, but the shop has already charged me $260 for R&R and I'm not ready to fork out the same again.

 

Alternately, I'd be happy with a manual toggle switch and bypass the whole unit, but I wouldn't know where to begin.

 

Any help from my Subie brothers would be appreciated.

 

p.s. how do you get the spell check to work on posts?

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Probably difficult to bypass the whole unit with toggles.  I have replaced units in my 98 and 99 OBW, that were ruined with soft drink spills on the buttons. Your 92 Leggie controller is pretty similar to mine. Suggest your score a couple of units from a wrecking yard. They don't cost much, so with two, you surely will find one that works well. I have always found that a lot easier, then trying to be an electronic tech searching for blown diodes, and bad circuitry.

 

Spell check on this forum works with my PC. Misspelled words gets underlined in red ink. Are you using a Chrome word pad or Linux operating system?? If so, maybe the cause of no spell check.

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I can't seem to open beergarage.com. I'll try later. I just want to remove and replace the a/c heater control unit. I actually would prefer a way to bypass the a/c turn-on functionality since I've been fighting an intermittant a/c for years now. I'm ready to sell an otherwise great '92 subie.

 

I'm still not getting auto-spell corrections. Help please

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Kind of a long read but lots of good info here on diagnosing the AC system.

 

http://bbs.legacycentral.org/viewtopic.php?f=10&t=49812

 

Removing the panel is pretty straightforward. Remove the screws from the upper trim bezel (it wraps all the way across around the cluster).

Then 4 screws hold the panel in, a couple of electrical plugs and a clip to pop loose so you can get the heater flap cable loose.

On the 95-99 Legacy it helps to unclip the cable from the air box under the dash first, but I'm not sure how/if that is accessible on the 1st gen cars.

Edited by Fairtax4me
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This may help. http://www.main.experiencetherave.com/subaru_manual_scans/FSM_Scans/legacy_instrument_panel_blowup.jpg

 

It kinda looks like the center trim panel may be removeable without pulling the whole top section.

Two screws appear to be behind the cup holder, and two screws go up from the ash tray slide.

Screws for the upper panel may be hidden behind there.

Edited by Fairtax4me
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Someone suggested that a bad evaprorator thermo switch could be causing the issue. Any comments on this? Basically my a/c just doesn't work, fans don't turn on, nothing cycles nada! It was actuating ocaisionally with lots of repeat button pushing but I can't get that far now.

 

I have a used controller coming in a few days. Assumming I can get it installed without destroying the bezel, we'll see what happens.

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