Fresh air door/flap

SWAUS6 · Post by **SWAUS6** » Thu Mar 03, 2011 2:47 am

H all,

Hope someone can help.

Doing the blower transistor fix on my Oz delivered RHD 1986 CSI. With the motor squirrel cages and covers out, I notice that the fresh air door/flap won't close off (swing up) - stops short about 25 mm when the centre control lever is all the way right, or the A/C is on (or both); and the same flap won't quite open right down - stops short about 3mm when the lever is to the left. The foam rubber door cover shows evidence of it having been pressed against the housing when shut, and when driving around previously noticed the air movement through the fresh air vent was much the same regardless of the position of the dash lever. BTW, back then with the engine off, the servo could be heard moving the flap so I thought it was ok.

I think something is stopping the door/flap from fully operating, and my forum searches have proved fruitless. Any ideas or solutions much appreciated.

Once this is fixed I will do the extra air to the side of the console trick to make the A/C work effectively. Its warmish in summer in Perth WA!

Cheers

Nathan

Pod · Post by **Pod** » Thu Mar 03, 2011 10:51 am

Have you checked that the Bowden cable is well lubricated and that the fixings/adjusters are secure? It sounds as if at each extremity of the control, the cable may be shifting/binding and so full movement is not being achieved.

Good luck, and let us know how you get on.

Chris Wright · Post by **Chris Wright** » Thu Mar 03, 2011 5:19 pm

In 10/85 the Center slider goes from cable operated to servo motor operated.

The Center slider is nothing more then a liner potentiometer sending a signal to a controller (Ref. #14) on the left side of the heater box. This controller is also connected to the left end of the flapper door hinge to monitor its rotational position. The actual servo that moves the door (Ref #15), is connected to the right side of the flapper door through a linkage.

Check the slider output, it may be dirty at the ends and not passing any signal to the controller. Give is a squirt of contact cleaner and run it back and forth a bit.

Check that the controller and servo are securely mounted and that the linkages haven't slipped.

Do you have the center console out? Can you watch its movement with it apart as you have it?

<a><img src="http://bigcoupe.com/ims/pic.php?u=21GvpX2&i=369" border="0"></a>

SWAUS6 · Post by **SWAUS6** » Fri Mar 04, 2011 12:04 am

Pod and Chris,

Thanks for your replies and fine information.

I don't have the console out, and can only see that the flap doesn't fully open and close from under the bonnet with the fresh air/heater blower out.

Looks like I'll have to remove the console to get at the areas and parts you describe Chris (thanks for the exploded view, very instructive). Is there a "how to" on removing the centre console?

Many thanks.

Chris Wright · Post by **Chris Wright** » Fri Mar 04, 2011 2:33 am

Removing the console:
http://www.e-24.ru/eng/practice/862.shtml

If your car has the switches on either side of the hand brake, that piece with the brush comes out differently than shown above. There is a single screw under the brush at the top of the hand brake slot and the bottom has 2 tabs that fit in to slots, they don't squeeze together as shown in fig. 4.

More info scroll down to "Vehicles after change point in 1982" :
http://www.malloc.nl/BMW/635CSi/pages/e ... l#refertoc

SWAUS6 · Post by **SWAUS6** » Fri Mar 04, 2011 6:43 am

Chris,

Wonderful, you're a legend. I'll get into the console zone on the weekend and let you know how I get on. Looking forward to sorting it out. BTW, my E24 does have the seat control switches either side of the handbrake handle.

Thanks again

Pod · Post by **Pod** » Fri Mar 04, 2011 8:49 am

[quote="Chris Wright"]In 10/85 the Center slider goes from cable operated to servo motor operated.quote]

Thanks for putting me right, Chris

SWAUS6 · Post by **SWAUS6** » Tue Mar 08, 2011 10:17 am

Just today found the time to remove the console and have a look. The servo motor on the RHS (drivers side in my case) moves when it is turned on, i.e. the whole servo moves as though it isn't fastened firmly. Given its on the drivers side its a long way back in there next to the steering column behind a heap of looms, plugs etc. Any tips on the easiest way to tighten its mounting before I delve in there? BTW, the full movement of the servo and linkage takes the door first closed and then slightly open. I'm assuming this is more evidence of a servo mounting issue?

Thanks in anticipation.

Chris Wright · Post by **Chris Wright** » Tue Mar 08, 2011 4:42 pm

This might help some:
http://www.malloc.nl/BMW/635CSi/pages/e ... l#refertoc

SWAUS6 · Post by **SWAUS6** » Fri Mar 11, 2011 8:50 am

Thanks for all the great tips so far. Found the problem, and now know a lot more about that part of the car. Alas, have not found a way of getting at the servo motor mounting screws without major removal of significant things. It doesn't seem that removing the A/C/heater unit is going to be remotely straightforward. Thinking it through a bit it, maybe it could be better to remove the dash pad or drop the steering column to get at the mounting screws? Any ideas welcome.

Also found out that the transistor swap fixed the fresh air/heater blower control, although the A/C will still only work on high??

Chris Wright · Post by **Chris Wright** » Fri Mar 11, 2011 3:33 pm

SWAUS6 wrote: Also found out that the transistor swap fixed the fresh air/heater blower control, although the A/C will still only work on high??

There are 3 transistors in the system, one in the speed control in the dash and one at each of the blower motors. If you can control the speed of the heater blower, then the transistor in the speed control and at the heater blower are OK. that means that the transistor at the A/C blower is bad also.

The Good news/ Bad news is that the A/C transistor is also located on the right side of the A/C blower right next to the fresh air flap motor and you can remove a plastic rivet and slide out the transistor carrier to replace it.
http://www.malloc.nl/BMW/635CSi/pages/e ... l#refertoc

(You might want to ask in a new post something like: "How to access the RT side of the A/C blower in RHD cars" to make sure more people see it.)

SWAUS6 · Post by **SWAUS6** » Sat Mar 12, 2011 12:28 am

Thanks Chris, Sage advice, I'll do a new post and see what someone may know.

Cheers