Following up on my 'oh my God its the ABS' pump question.

I was pointed in a different direction

Hi Rob might sound silly but are you sure that you are hearing the abs
pump and nothing else ie: the heater control valve opening and closing
to maintain temp in car (try turning heater control dials to max hot
and see if noise stops cycling) also is the noise present with
ignition
on or engine running? there is also an air pump behind the glove box
which starts to run when you put the ignition on.

Turns out this is correct. Its this pump on the heater, that is
punctuated by the heater control valve opening and shutting.
If I modify the settings on the temperature wheels, I can cause the
valve to stop operating. The pump continues to run tho.
This all seems to be in order, tho I don't understand why the valve
needs to keep opening and shutting. I can definitely hear it ticking
away every several seconds when it is in this mode.
Is that correct?

Cheers...   Rob.