[DJB]

Looking at the Bentley manual wiring diagram, in particular at the heat exchange sensor for an 86 which is connected to the heating control unit (between the seats) - it refers to the wire colour as NCA - what's NCA?

My heat exchange sensor is not connected to the plug in the auto heat control unit - in fact the plug has been cut off. I have found a used plug from a BMW and ground it down to fit. I was wondering if the orientation of the wires from the sensor to the plug matters?

The wire from the sensor is white with a heat protective coating and has a white and black wire inside. The heat exchange sensor is meant to tell the auto controller when the heat exchanger is up to temp, to allow the footwell blowers to function (currently mine do not).

Would this sensor simply be a normally open/closed switch - in which case the wire orientation on the plug should not matter. However, if the heat sensor increases or decreases resistance - will the orientation of the wires in the plug matter?

Any ideas from an electrical genius is welcomed.