450 SLC auto - 1980

[patroddy]

We have a problem with a heater fan speed control on a 450 SLC Auto - 1980. It runs at full speed all the time even when switched to zero (Sometimes does not start on initial switch on of the engine but then comes on after a couple of miles). The car does not have air conditioning.
We see from the Haynes manual on the wiring diagram - item 67 is blower switch with light and item 76 is pre-resistance, blower motor but the manual does not indicate where these are or how to get at them.
Also, heated rear window: Although the light comes on on the switch, the rear window does not de-mist. We feel this may be to do with item 82 (Haynes manual wiring diagram). Once again, the manual does not say where this is or how to get at it.
Help would be much appreciated.
pat@new-air.co.uk

 

[cowsurgeon]

Hi there,
Not sure if I can help you with the fan speeds, but I may know what the problem is with the de-mister. I own a 1980 350SL and mine doesn't work either, it may be different seeing as the slc is 'all in one and doesn't have a separate hard top, but check and see if there's a cloudy white patch in the corner of your rear windscreen, if so it may be that the element is damaged in this area as the glass is de-laminating. Malcolm Brown posted a good answer to this when I asked the question, you should find it if you search for 'cowsurgeon' under author search.
Hope this sheds some light,
Chris.