In various implementations, a heat exchanger system may include one or more flow paths. At least one of the flow paths may be associated with more than one pass and/or fluid flow through the flow path may be restricted. A setting of the heat exchanger system may include associations between flow path(s) and/or pass(es). A setting for the heat exchanger system may be determined, and the heat exchanger system may be allowed to operate in the determined setting, in some implementations.