1985-1998 [Subscribe to Daily Digest] |
 | [Main 9000 Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: 1990 Saab 9000 CD Turbo, problem with EDU, etc... Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Mon, 14 Mar 2005 08:30:30
In Reply to: 1990 Saab 9000 CD Turbo, problem with EDU, etc..., Ken Barton, Sun, 13 Mar 2005 13:05:30 Members do not see ads below this line. - Help Keep This Site Online - Signup |
If you try and manually control the Blower fan speed, can you? If you set the Temp to HI or Lo, and hit the fan speed UP button, does the fan come on?
The only connection I see in the schematics is that the EDU system tells the ACC what the outside temperature is. The ACC uses this for things like mixer flap position and fan speed. From the documentation I have, if the signal is failed at start-up, the ACC defaults to 0C, otherwise it just uses the previous value.
When the EDU display goes away, does the blower fan just stop running? Or does it keep at the old speed?
What I don't have at hand is a diagram of the grounds. THAT would be helpful.
In the past, I have had a failure on the EDU board itself. In my case, it was a bad diode. That was just a plain open circuit, removing all power from the board. In your case, you might have either a bad solder joint, or a bad component that opens when it warms up.
I would try this trick - before starting the car, remove the Cabin Fan Blower fuse (30A). See if the EDU runs longer than a few seconds. If that is the case ,then I would suspect that they share a ground. The EDU pulls very little current, the blower pulls A LOT. If they shared a ground, and it wasn't good, the current from the blower motor would quickly cause localized heating, and that would raise the resistance of the bad connection, and create a big voltage drop. Both the fan and EDU would stop working. Once the motor stopped the contact would cool a little, but the fan would still be pulling current, creating a voltage drop. But it wouldn't be enough to get the fan to run again. This is just speculation, assuming they share a ground. I don't have a '90 manual, but I have an '88 and a '92, and the grounding is probably pretty much the same.
posted by 192.249....
, Mon, 14 Mar 2005 08:30:30 <-- Viewing This Message
, Sun, 13 Mar 2005 15:26:01
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
