If you are suffering from steaming up screen or water in the passenger footwell this could be the likely cause of the problem. I have removed nearly half a bucketful of soil and dead leaves from previous cars. The screen drain on the E36 is just about adequate untill the drains become blocked and the rainwater cannot escape. This also causes water to enter the compartment where the ECU is kept and can cause starting and strange running issues.
This guide was carried out on a saloon, the coupe and cabrio are slightly different as the wiper arms need to be removed to allow you to remove the blower intake grille. Touring and compact are the same as the guide.
Here is the panel.
First of all, remove the rubber trim surrounding the intake grille. This gently pulls off.
Now remove the intake grill. Gently pull the plastic clip towards you to release them and then the grille will come off.
Now the grill has been removed you will see two phillips headed screws that hold the wiring harness cover in place. Remove both of them.
Now gently pull the waring harness cover away from the bulkhead panel. Be gentle as this will only move about an inch forward.
Now on the driver side of the bulkhead you will see 2 7mm headed bolts. Remove these. Some cars have a bracket, some dont. So be aware not to drop the bracket if yours has one. There is only 1 7mm on the other side. Remove all 3 bolts.
Now the panel can be removed. This may be tight and will need a good tug to remove. Be careful not to damage the panel or the wiring loom.
Now you can see behind the panel and to the heater blower motor. All this space needs to be clear of rubbish and debris.
Once this has been cleaned out, you need to check that the rubber drain tubes are clear. I use a piece of welding wire, but an old wire coat hanger will do. The pics are not very clear on the location as they are hard to see on a 6 cyl. You will see them when you start poking around.
Here is a rough location.
And here is what one looks like.
If you keep them clean, the car will be much quicker to demist and will prevent ECU faliure due to water entering the compartment.
Thats all folks. Reffitting is reverse order. The panel can be a pig to replace, but take your time and it will go back in....