ACC Climate control going bad?

[7aull]

Cheers All-
did not see an Archive area to check so forgive if this has been covered elsewhere.

86 9000T US model, 123,000mi

My ACC panel lit up like a christmas tree the other day - button indicators all (or most) illuminated inspite NOT being selected. Temp readout digital display distorted. Buttons still seemed to function, but with no follow-thru with lights to confirm operation. Magically it was fine today, but I know it will be back...

Solutions? I expect even if the panel WAS still available, it would be Heroically expensive. So. Used? IS it the panel? or some buried relay(s) somewhere?
What model year range of panels will replace it? I know that later 9000 panels LOOK the same, but part number differences seem to suggest otherwise.

And any guidance on the mechanics of exchanging them?

Thoughts, suggestions, references to archives on this problem appreciated!

regards
Stu Aull
86 9000T
Alaska

[7aull]

bump-

really?
no one EVER had/seen this problem??

Stu Aull
Alaska

[c900]

Could be a faulty electrical connection somewhere. Have you pulled out the ACC unit and made sure the electrical harness connection at the back is ok with no obvious broken wires or connector pins not properly seated in the housings?

Have you chekced the ACC fuse is properly seated in it's socket?

It could be a dry joint on a PCB inside the ACC unit itself though I haven't had a need to do any sort of board-level repair in my 9k's ACC unit to date.

Craig.

[7aull]

Thanks Craig-
if you'll forgive apparent laziness on my part, I have done NOTHING yet since I didn't want to crack open the dash or ACC until someone could maybe offer more specifics.

Excellent and obvious idea of course -
does the 85-90 ACC units "just" snap out from the front or does the dash top need to come off or....
????
hate to bugger it just trying to pull it free!
thoughts?

Stu in Alaska

[Superaero]

Never heard of a failure of this component. I agree likely a loose cable connector. Do the self test and report the displayed codes. Ignition ON. select AUTO and VENT simultaneously and allow the self test to complete. If the ACC has failed it should display that code, otherwise you will see a number from 0 (no faults ) to likely 1 or 2 (if any faults). Select VENT sequentially for the number you see and record and post to us the code displayed after each press of VENT. If 0 displayed then pressing VENT should restart the ACC.

[chengny]

I'm not sure what the 1986 version of the ACC controller looks like so this may not be of any help. But it may be a workaround using a newer (more readily available) unit :




*** FOR ADDITIONAL INFORMATION NOT INCLUDED HERE, REFER TO TSB #01950537, DATED AUGUST, 1995 *** .

• From 1993 a new ACC control module is introduced in order to eliminate erroneous diagnostic trouble codes being generated from the rear A/C. This applies to all cars of year models M199O-M1993 with ACC2. The new control module has the following designation:
• ACC control module M1994 part number 43 82 933
• or as a spare parts kit for rear A/C: Part number 74 96 326 (contains ACC control module as above).
• If this control module is to be fitted in cars from M199O-93 any jumper connections and resistors in the wiring harness must be removed.

Action

1. Unplug the 39 pin and the 12 pin connector on the rear side of the ACC control module.
2. Remove any jumper connections between pin 30 and pin 32 on the 39 pin connector. Insulate cable.
3. Remove any resistor between cables 23 (black) in the 12 pin connector and cable 407 (yellow/white) in the 39 pin connector. Insulate the cable.
4. Fit the new ACC control module and calibrate.

Anyway, having offered that probably useless bit of info, I would suggest checking for proper continuity to ground. The ACC panel uses ground point G-8 (under the drivers side speaker). Poor grounding of electronics often manifests itself in the kind of weird ways you described.

BTW: Saab acknowledges that this component is extremely intolerant of static charges. They even go so far as to recommend the use of a hand ground strap (as used in computer repair) during R&R.

[7aull]

you guys are GREAT - thank you!
You're right, the Post 1990 ACC info is likely no use (but thanks) -
will attempt diagnostic and post results.

Just assumed these units were eventually problematic since I saw DOZENS offered up on ebay...

Was always afraid this early electric/electronic system might have been a bit ambitious even for Saab. but - it HAS been 25 yrs!

Stu Aull
Alaska

[Superaero]

Many of these electrical components are so reliable they outlast the cars they were fitted to.

Those of us who own Alfa Romeos joke that there are plenty of spare engines and transmissions around to be fitted to the few non rusty bodies left. Same principle.

People worry alot about the modern electronics going bad in their cars thus obsoleting them. In reality the automated quality control required to manufacture these puppies pretty much guarantees that failure will occur shortly after original installation. if it doesn't fail during the warranty it probably will long outlast the car. That is why so many spares of these components are available. However, NEVER buy one of these electronic units from anyone who won't absolutely guarantee they are working. this is another reason they are hard to re-sell so there are lots available. The ONLY way you can test many of these units is to fit them and drive them. In many cases the car manufacturer cannot test these units and must return them to the original manufacturer who can test them. Generally speaking the repair mode for solid state devices is the garbage can.....