... but can you actually turn the heater off ???!!!

My 1986 4/4 seems to chuck out the hot air through the windscreen demister vents regardless of whether I slide the control bar (under the dash marked 'H') in, out or in between !
And this is with the fan turned off !

Is there another control that I've missed ?

Now that the weather is a little warmer, I'm starting to roast.

I sit and wait for replies with suitable embarrasment .

Matthew