I know this post is super old, but I’m hoping the original poster is still on here to let me know how this all turned out? It’s like you are describing our 4.5 year old! Since he could walk, he has been obsessed with vacuums. He got a toy vacuum for his first Christmas, and since then it’s been the exact same as your experience. Around 3 years old, he developed an intense fascination with tractors that lasted until about 6 months ago, and like a light switch, one day he was back to vacuums. I’d love to hear how this ended up going for you! I’ve suspected Aspergers with him, but he’s so social, imaginative, and loves to play with other toys, as well. Just not like vacuums. He truly would play with them all day, if he could! It will be what it will be, but it does concern us at times, since it’s such a strange thing to be that passionate about. We just encourage his interest, try to keep things balanced without squashing his passion, and trust that there is a grand plan for it on down the road!