Quote Originally Posted by Erni View Post
Check where the heat is coming from. The garage doors if they face the sun will become giant heaters. A bit of foam on the doors will help. Walls are not insulated where they do not meet the house. May want to pull dry wall insulate and replace. Ceiling too. Does it have insulation above the garage to the attic ? And yes do a fan with thermostat control if the rest fails.
On my previous house, I used that aluminum foil bubble wrap inserted into each of the door panels, and it dropped the garage temp by 15-20 degrees when they were getting direct sun. Didn't require re-tuning the door springs or anything.