I just got a used cat scratcher from a neighbor who is moving. I need to add new sisal rope to it before I give it to my cats but first I want to make sure it doesn't have any fleas.

Maybe this is a stupid question (I've never had to deal with fleas with either of my cats or my dog) but if I leave the cat scratcher in my car for a day or 2 will it kill any fleas that might be there? How can I tell if there are fleas? It's supposed to be in the mid-90s all week so if I leave the car in the sun it will get well over 100 degrees in there. Is that enough or should I do something else?

Thanks in advance for your help.
Thanks for the ideas. The thing is huge (I guess maybe it's more like a Cat Tower than anything else) and is about as tall as me (right around 5'). So I don't think it would fit in my freezer unfortunately