[GaryGriff]

Yipeeee hi oooohhhhhh, at least that's what the experts say.

The heater controller in the engine compartment was at fault and now all works perfectly.

It seems the heater blower circuit was fine, displayed by the fact that when the relay inside the controller was depressed with a finger the blower functioned.

The switches in the control unit between the seats were working fine ('cos I checked if they were making and breaking the circuit with a multitester set on resistance. The switching power for the relay comes from this source.

The actuating arm operating the flapper boxes in the rear was working fine.

Anyway, it's all go now, I've learnt where all the parts are and have a pretty good idea where to look if something happens next time.

I will take the old realy to pieces though an let everyone who subscribed to this post know what I found out. It would be nice to know what broke and if it could be sorted with a soldering iron and 50cents.

Thanks to all who made comment and tried to help.