Raccoons need a 4 inch diameter hole, so their entry point should be obvious. If they are going in and out a lot there will be an oily/dirty looking stain around the hole, or scratches from their claws. The opposite can be true too. An entry spot can look cleaner than the surrounding area. If you have a spot where there's loose rubber flaps they might be pushing their way through but it should still be obvious.
How do you know it was a raccoon? They are nocturnal so typically if they've found a cozy place, they'll sleep there during the day.
You'll need to do some crawling around with a good flashlight and you'll need to probe places you can't see with your fingers.
If its a compartment you can crawl into during the day, and close the door behind (with a helper outside) you sometimes you can see light. When you do your searching one common mistake is to underestimate where an animal can find entry. Check everything even if at first you don't think they can get in that way.
Tom and Pris M. along with Buddy the 18 year old Siamese cat
1998 Safari Serengeti 3706, 300HP Cat 3126 Allison 3060, 900 watts of Solar.
Dragging four telescopes around the US in search of dark skies.