I understand they operate when the windshield washer is activated. But--it also says the lamp washers operate on a timer when the headlamps are on to conserve washer fluid. Does anyone know how this works? It doesn't make sense to me for the washers to operate at night in nice weather when they're not needed. That surely would waste fluid. Does anyone know if it means that when the headlamps are on and you spray the windshield, the headlamp washer will only spray every third activation (or something similar) in order to save fluid? I've asked Volvo and all I get is a repeat of what's in the manual. One person did say she seemed to recall that's how it works, e.g. every third manual swipe with lights on washes the headlamps. Can anyone shed any light on this? Thanks.