I’ve just installed a Defender heater assembly in my 109 SW, I’ve used a RHD assembly, but split the motor off the casing and turned it 90degrees like the Series blower. I’ve fabricated a bracket to hold it to the footwell, and a ducting to the orginal matrix housing. It seems to work ok, but I think I could have done better….I’ll be doing a mark 2 version for my other 109! Just got the wiring to do now, but it works straight off battery.

Cheers

I took measurements from a Defender, of the distance from the bulkhead to the rear of the intake and from the outboard edge of the intake to the joint between wing top and wing side panel and transferred these measurements to the SIII wing top (covered in masking tape to prevent scratching when cutting and also to make drawing easier). Remember to allow for the thickness of the edge of the intake grille – it and the duct below need an overlap of aluminium to screw into. The hole was cut using a drill to make pilot holes and a jigsaw.

I used 17A wiring and fuse for the motor control, connecting the purple motor wire (permanent live) via the fuse to the battery terminal on the starter motor solenoid. The striped green wires connect to the SIII wires of the same colour, and you then disconnect the live from the SIII switch and connect that terminal to earth (the Defender unit is wired backwards compared to the SIII, where the switch runs to earth instead of the motor, increasing efficiency and also extending switch life).