Frosy the Snowman movie?

There was this one version of Frosty the Snowman that i had on tape when I was little, it was a cartoon version, I just remember there was a little girl and a little boy and they were in a children's hospital or something, and there was this musical number and they go around on this giant toy train. and they have to help Frosty battle the evil guy but he ends up melting Frosty. I can't figure out what year it is or where to find it :/ if you can help that's great !