Clam Chowder is usually served piping hot and makes for a good dish to eat when it's cold outside.
Every time I've ordered clam chowder when going out to eat the clam chowder was always served piping hot and not cold.
However some people do make chilled clam chowder and love to eat the chilled clam chowder on hot summer days.
So yes you can serve clam chowder chilled or cold but most people including myself prefer the clam chowder to be served when it's hot.
Hot clam chowder is very delicious but maybe the chilled clam chowder is as well.
Maybe I'll try it sometime to see how I like it this summer.