A system of modular fans for a network device is disclosed. The network device includes a rack assembly having side walls forming an enclosure with a plurality of sled slots accessible from a rear end. A plurality of operation sleds are mountable on one of the plurality of sled slots. A plurality of removable fan modules is provided. Each of the removable fan modules are installed in one of the operation sleds. The removable fan modules are individually removable from the operation sleds and therefore may be swapped out while the rest of the components in the network device remain operational.