my doubts that that aux air valve is properly functioning electrically. But I can test that.
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the electrical cnxn to the Aux Air Valve is for a Heater. The idea being that when the egine is cold the blade/slider is open and as the engine warms up and the heat from the engine compartment along with the Electric Heater and some vibration of the engine the blade/slider closes.

Inside the body is basically a wound spring type thermostat that moves the blade. If you live in a warm climate the slider dosen't open at all.. There is a Temp range. I think it's 68F and below that it opens...you'll have to look that up.

So basically it is a Mechanical Thermostatic Valve --- If you disconnect the top hose, with a flashlight you can see the blade/slider. If it's dirty you can remove the unit and clean the insides with one of those spray cans of auto cleaner/lubes.

When the one on my old 75 wagon failed, it wouldn't close and whenever I stopped at a light the engine would not drop to idle it stayed at 1000+ RPM.

The Volvo Problem Solver has a Hack --- losen the nut and you can slightly repostion the end point of that blade...check out that page