Dirty/Clogged Soffit Vent
Have you EVER cleaned your soffit vents? 95% of homes have clogged, blocked or painted over soffit vents. Or, the holes behind the vents are so small almost no air is coming into the attic. I’ve even seen million dollar homes where they just screwed in the vents and did not bother to even cut holes. I’ve seen many homes where just cleaning the soffit vents (use a dry nylon car wheel brush) will drop the attic temperature 20º in 20 minutes.
Read more about the basics of attic ventilation here: