I suspect so, yes, although I've never actually thought to look.

But the heater core (itself merely a small radiator) is much smaller then the engine radiator. The same coolant flows through both, leaving the same deposits as it goes. The smaller radiator would surely clog first as it has far fewer tubes and smaller tanks.

Well, that's my ultra-scientific take on the matter

No doubt other factors come in. The velocity of the flow, position of the heater core, the coefficient of linear expansion....stuff like that !

Cheers
DD

 

Ah, cooled then heated, not heated then cooled. That was it.

Oddly enough, I still have air out the centre when turned down from full cool. Difficult to tell these days actually, as for some reason I have to turn it almost all the way down to the warm side to get it to stop trying to freeze the interior. I don't mind the freezing part so much, but the fan is on louder than I'd like (and yes, changing the fan speed up does increase it), so to get to try for a temp where it won't blast requires turning the temperature knob well past halfway. Odd.

 

Yeah, that is what I had in mind. Wouldn't otherwise make much sense. Otherwise you'd just get too much heat or too much cold (if one or the other was actually fully off).

I remember talking to a Volvo technician (they know how to make a good heater!) and the heater valve there was always on, even if the heating is turned off... That is why I found it a bit weird to have the heater valve switch off and therefore reducing the full flow of the heater core to a lower output.