I think the auxiliary pump runs anytime the ACC is in Auto and it varies the monovalve's Open/Close duty cycle to modulate the amount of heat produced to keep the cabin at the desired temperature.

I think the auxiliary pump runs and the valve also modulates in cooling mode to provide re-heat for better temperature control than just cycling the compressor.

So, I think the aux pump should always be running (constant voltage) and the monovalve is intermittent, so you would see voltage in some ON/OFF/ON/OFF combination.