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From digest.v6.n852 Mon Jul 7 05:12:06 1997
From: Laurence Taplin <>
Date: Sun, 6 Jul 1997 16:52:06 +1000 (EST)
Subject: Re: bmw-digest V6 #847


Not sure whether my 733i is same dash setup as yours but, if so, this may help. Mine is not the climate control version but has a push button dash for heater/AC controls and two horizontal dials for fan and temp control. I had same problem as you. It was caused by a brass pin in the temp control knob breaking out of its plastic fitting. This pin is the attachment for the wire cable which controls the temp setting (running out under the dash and connecting to a link beside the steering column (mine's a RHD model). My fix (from memory):

Remove battery negative.

Remove heater cable from connector under dash near steering column (can't get dash out otherwise).

Pull out dash and disconnect all the wiring to the switches etc there (all are colour coded or have special fittings to prevent wrong connections, so you can't go too far wrong).

Remove screws holding in the fan and heater control module (4 from memory). You can then retire to a more comfortable spot to work on it ;-).

To get to the heater control knob, you have to remove the fan control knob above it. There's a plastic pin on one side which you can remove easily with pliers, after which the two halves separate quite easily (maybe a screw or two to extract). Plastic pin goes back in OK if you're careful not to damage it.

The heater control knob has a spiral slot cut into it - around which the brass pin slides. The brass pin is attached to an arm which translates the rotary motion into horizontal motion of the heater cable. In my case, the pin had broken out of the arm because of 'plastic fatigue' and stiffness in the cable/linkage. Pressure on the pin makes it break outwards through the side of the plastic arm.

Dealers wanted Oz$450 for a new unit complete. Second hand dealers would sell the whole dash only for $500. My fix:

Cut a small piece of thin steel and bend it around the arm where it's broken. Cut the broken side out of the hole the pin fits in so the brass is exposed. Silver solder the pin to the metal and then drill and bolt the metal plate and pin to the plastic arm - I used ca 8BA brass nuts and bolts. Took about 40 mins and cost about 80c. Has been working ever since. (BTW - two earlier attempts to fix the pin in place with adhesives, epoxy etc failed, even using the metal strap to strengthen the plastic arm).

Easy to fit a new globe or two in the unit at the same time. Watch out that you get the same wattage as the others in the dash - its really annoying to have a couple of bright lights and the others dim.

At 07:41 PM 03/07/97 -0400, you wrote:
>Date: Thu, 3 Jul 1997 16:47:58 -0400 (EDT)
>Before I turn my dealer service (you call them "stealers') loose on this
>problem I'd like to hear from the knowledgeble folks out on BMW net.
>The heater control on my car seems to be of no value. Hot is the only level.
> The only way to control the heat is to shut down the flow and open the
>outside air and turn on the air conditioning , which works but is not
>temperature controlled. Incidently the back light behind the temp control is
>also out. Any ideas or guidance would be greatly appreciated.

Laurence Taplin
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