Or any other familiar granted through archetypes for that matter. Is the familiar's "level" based off of total character level or the level of the archetyped class in which it was gained?
For example, if say, I was a 3rd level Eldritch Guardian, and subsequently took the rest of my levels(12) in Summoner or some other class, would my familiar ve that of a 3rd level characer or would it be considered that of my total character level(15th)?
the HP is half your HP, but the intelligence increase and the natural armor increases are stuck at lv3.
Unless your new class also gets the familiar class feature. In that case you add the class levels to determine your familiar's abilities. So if you had 3 levels in Eldritch Guardian and 12 levels in Wizard, then your familiar's ability would be calculated using all 15 levels.