The Shield Surveyor is a little different from a Repair Surveyor. This type of Surveyor is capable of adding or restoring shields on any Hyperion Mechanical enemy except other Surveyors. It will go from unit to unit, adding or restoring their shields until all shields are maxed out. At this point, it will erect an orange shield around itself and start attacking you with ion bombs. Rather than trying to cut through its strong shields, it is much more efficient to attack an enemy Loader so that the Surveyor stops its attacks, lowers its shields and repairs the Loader's shields.
These Surveyors only add and repair shields. They will not repair armor damage or health.