An apparatus to control a temperature within a housing, the apparatus comprising: a housing to contain a field device of a process control system, wherein the housing includes a relatively warmer fluid aperture and a relatively cooler fluid aperture; wherein the relatively warmer fluid aperture is different and separate from the relatively cooler fluid aperture, and both allow a direct access to the internal compartment of the field device; a vortex tube that is external to the housing and that includes a first outlet, a second outlet, a first passageway fluidly coupling the first outlet to the relatively cooler fluid aperture of the housing, and a second passageway fluidly coupling the second outlet to the relatively warmer fluid aperture of the housing, wherein the vortex tube is configured to divert a first portion of a fluid to the first outlet and divert a second portion of the fluid to the second outlet; a first flow control member having a first cool fluid outlet and a second cool fluid outlet, wherein the first cool fluid outlet directs cool fluid to an atmosphere surrounding the housing, and wherein the second cool fluid outlet directs cool fluid to the first passageway to fluidly couple the first outlet to the housing to supply at least a portion of the first portion of the fluid directly to an internal cavity of the housing; and a second flow control member having a first warm fluid outlet and a second warm fluid outlet, wherein the first warm fluid outlet directs warm fluid to an atmosphere surrounding the housing, and wherein the second warm fluid outlet directs warm fluid to the second passageway to fluidly couple the second outlet to the housing to supply at least a portion of the second portion of the fluid directly to the internal cavity of the housing separately from the first portion. a housing to contain a field device of a process control system, wherein the housing includes a relatively warmer fluid aperture and a relatively cooler fluid aperture; wherein the relatively warmer fluid aperture is different and separate from the relatively cooler fluid aperture, and both allow a direct access to the internal compartment of the field device; a vortex tube that is external to the housing and that includes a first outlet, a second outlet, a first passageway fluidly coupling the first outlet to the relatively cooler fluid aperture of the housing, and a second passageway fluidly coupling the second outlet to the relatively warmer fluid aperture of the housing, wherein the vortex tube is configured to divert a first portion of a fluid to the first outlet and divert a second portion of the fluid to the second outlet; a first flow control member having a first cool fluid outlet and a second cool fluid outlet, wherein the first cool fluid outlet directs cool fluid to an atmosphere surrounding the housing, and wherein the second cool fluid outlet directs cool fluid to the first passageway to fluidly couple the first outlet to the housing to supply at least a portion of the first portion of the fluid directly to an internal cavity of the housing; and a second flow control member having a first warm fluid outlet and a second warm fluid outlet, wherein the first warm fluid outlet directs warm fluid to an atmosphere surrounding the housing, and wherein the second warm fluid outlet directs warm fluid to the second passageway to fluidly couple the second outlet to the housing to supply at least a portion of the second portion of the fluid directly to the internal cavity of the housing separately from the first portion.