Headlight wiper my headlight wipers won't work anytime the wipers are on

They shouldn't - they only work when you do a wash/wipe.

The headlights of your Volvo do an important function on your vehicle. The headlights provide the illumination that the driver of the vehicle needs to see what is ahead of the vehicle, especially when driving at night or when driving with low visibility conditions. But there are times when dirt sticks on the headlight lenses, decreasing the efficiency of the headlights. So that you will not have to come down from car just to wipe the dirt off the headlight lenses, headlight wipers with Volvo Headlight Wiper Blade are installed on your Volvo.   The headlight wipers’ functions are similar to the function of the windshield wipers; the only difference is the location. For the headlight wipers to efficiently clear out the dirt and the precipitation, the Volvo Headlight Wiper Blades should always be in good shape. If you need a new wiper blade, you can get the Volvo Headlight Wiper Blade. Each Volvo wiper blade is made from high quality materials and they are guaranteed to last long.
this headlight wiper blade is also used as a clearing material in order to prevent the headlight covered with dust and other element which can be cause for your headlight to produce inadequate light rays.