ACC fan stays on when ignition off

[carrera]

I have just finished prepping the blue car for MOT and took it out for a spin to get some tyres swapped over on rims. Stopped the car, all was OK.

When I came back I switched the car off and the interior ACC fan stayed on. I have removed the earth cable to stop the battery being run flat.

I did the ACC diagnosis and it goes through all the motions and comes up with error 08 which I think is a problem with one of the stepper motors, (left side), on one occasion it also showed a code 11.

However I don't think this is my problem. A quick read round says it's likely to be the blower motor / controller (wherever they are located)

Before I dive into that, does that diagnosis make sense, any other checks I can do to confirm what the problem is. My first instinct was that a relay had stuck in the engaged position.

Can't help thinking it's something I have done.... but the only possibility is that I may have disturbed something when attempting to remove the wiper arms and after failing at that trying to peek under the plastic cover 

Any thoughts. Wiper arm removal tool may be here tomorrow ?

 

[phoenix]

It does sound like an issue with the fan controller. Here's the description of operation:

The fan is supplied with +30 from fuse 22. The control module regulates a control unit
which supplies the fan motor on the ground side. The fan control unit is situated on the
driver's side of the heating and ventilation unit and is cooled by the flow of air in the
evaporator.

The fan control unit is supplied with B+ from pin 5 on the ACC unit and power grounded
from grounding point G41P. The ground lead is also reference ground from pin 35 on the
ACC unit. The fan control unit is controlled by an analogue voltage of 0-5 V from pin 14 on
the ACC unit. The fan current increases as the control voltage increases.

A simpler summary of this is that one side of the fan is connected to the battery +ve terminal all the time, the other side is connected to ground via the controller.

Here's a list of all the codes:

Code   Problem   OBD
1   Internal control module malfunction   B1605
2   Cabin temperature sensor - open or short circuit   B1350
3   Solar sensor   B1340
4   Mixed-air temperature sensor, LH - open or short circuit   B1345
5   Mixed-air temperature sensor, RH - open or short circuit   B2345
6   Stepping motor, air-mixing flap, LH - open or short circuit   B2490
7   Stepping motor, air-mixing flap, LH - motor jam   B2496
8   Stepping motor, air-mixing flap, LH - no mechanical contact with flap   B2495
9   Stepping motor, air-mixing flap, RH - open or short circuit   B2290
10   Stepping motor, air-mixing flap, RH - motor jam   B2296
11   Stepping motor, air-mixing flap, RH - no mechanical contact with flap   B2295
12   Stepping motor, air distribution flap - open or short circuit   B2400
13   Stepping motor, air distribution flap - motor jam   B2406
14   Stepping motor, air distribution flap - no mechanical connection between motor and flap   B2405
18   Solenoid valve, heat exchanger shut-off valve - open or short circuit   B2375
19   Circulation pump - open or short circuit   B2380
20   Ventilation fan   B2425
21   DC motor, air recirculation flap - open or short circuit   B2410
22   ACC software   
23   Sensor Ground   B2945

[carrera]

Thanks for clarifying that, confirms what I suspected.

You access this from the top, via the plenum don't you, small box with heat sinks on top, part number 48 69 327 ? - I'm still waiting for my wiper puller to arrive.

Are there any tests that can be done to confirm the diagnosis / test the fan control unit when removed?
 

[carrera]

Bit of an update:

Good news, I found I had a s/h fan control module on the shelf

Bad news, the wiper puller arrived, but the wipers still do not want to come off 

I've followed the wiring diagram and the explanation above. It seems I should be able to measure the voltage on green / blue wire from pin 14 and see it vary from 0 to 5 volts with the visual display of fan speed ?

If it does then that would confirm the fan control module has failed providing a full current route to earth ??

[phoenix]

Yes, that method is correct.

The wiper arms can be very tough to get off. The arms of the puller I used started to bend before they finally came off. You need to make sure it's absolutely square on, and I helped mine with a clamp across the jaws, grease the screw thread thoroughly then keep winding it beyond hand tight with pliers or something similar.

[fka]

I've been using a ball joint remover on the wiper arms for a number of years. You need to protect the plastic scuttle to stop it getting scratched but it works where my puller have failed.

https://www.partsforsaabs.com/product_info.php?cPath=141&products_id=4097&osCsid=0a2e6e598505fc643a4c98ffe57d8f48 

[carrera]

Thanks guys 

Just had a productive 15 minutes:

Tested for voltage from the ACC unit - behaved correctly 0-5.15v according to the fan speed display, so looks like it's the the fan speed controller

I had a ball joint puller, but mine worked the other way round, so no good for this job

Then I put a set of curved mole grips around the base of the puller legs. This stopped them spreading, followed by bending on one side, so both arms are now off. Tight, but removed without tools on the winding arm/pin. The thick gloves helped though. 

I suppose the next bit is where my hands get cut to bits on sharp plastic that I can't see 

[carrera]

Yesterday I removed the windscreen wiper assembly, the top of the fan cover and pulled the cables through from the passeger side. I did not need to remove the metal plate bolted onto the bulkhead to remove the top cover or withdraw the fan assembly at all.

Today I am changing the fan controller. It's fairly tricky to get at, but you don't need to remove the seats as some have advised elsewhere on the internet.

Here's a photo of the old one before I remove it. There is a clear plastic cover over this normally, but it has already been removed, just two 6mmm screws

When I reassemble I think the cruise control will work again as the clutch pedal switch was hanging loose 

[sgould]

Good luck!   Last time I went under the dash I got cramp and had to be helped out!!

[carrera]

I feel like an ***ing limbo dancer. 

3 hours later it's almost out. Screws were not too bad, though I did need cranked and normal 6mm spanners. Incredibly tight getting the unit out of the hole, the sound insulation has to be pushed back and then it's incredibly tight getting past the edge of the pedal box.  The cable got caught behind some plastic (maybe there by design in the factory) and it didn't want to be levered out which has been the most difficult part.

I'm not generally ham fisted, as there's always a world of pain if you break something you didn't want to, which can show the job down. Just got the two final plugs and rubber to lever out.

I took another look at WIS - when everything is undone the manual says "remove the unit". Pah !

Seriously, these aren't intended to be replaced once the car left the factory are they. If they are what's the standard time, bet no one ever makes it   

[carrera]

.... and one hour later it's out.

That's enough for today, good job I don't need the car 

[carrera]

Curiosity compelled me to see if I could access the internal electronics.

Fairly easy, two small torx screws that clamps the cables behind some foam, lever the plastic cover off and remove one screw and the board is removed.

There's a big MOSFET, screwed to the heat sink using thermal paste. A nose test said that some electronic component had failed giving the osual tell tale smell. Nothing appears to be damaged but a few minutes with a meter confirms that there is a short circuit between two of the pins which provides a direct route from the feed to earth. That confirms the reason why the fan blows full speed with this failure mode.

I found this old thread http://www.saabnet.com/tsn/bb/NG900/index.html?bID=109530

So it seems a replacement of this MOSFET will repair the component. When the car is all back together I'll try and get time to identify exactly what MOSFET is fitted. At this point I'm assuming it is the same NTE2920 ? However, that is not available from RS Components or Farnells here in the UK.

[carrera]

Well, the job is complete and my left hand is red raw.

I do have a working fan with the ability to vary speeds, so it has been worth it. I dread to think what it would have cost in a garage

It was easier to put back in than take out, for which I am grateful. The wiper blades are back in position, with a lovely coating of copaslip, so hopefully they will not be as difficult to remove next time. The squeek has also gone from the wiper assembly which I lubricated. 

I'm just going to adjust the handbrake and she's ready for MOT

[sgould]

The last time I looked at this, I thought that there was a comment in WIS to use some tool to bend the bodywork to get the unit out.  But raw hands seems to be normal.

[phoenix]

I've repaired a controller from a 9000 before- again a T03 device. IIRC the exact one wasn't readily available but there were a few choices of equivalents that were easily found.