To cool heat-emitting electronic components, a compact, non-moving-parts compressor (33), an evaporator (26) in juxtaposition to the electronic components and a condenser (31) are mounted as a unit, preferably within a vacuum can (36). A heat exchanger (37) is mounted external to the can but in proximity to the condenser (31). The foregoing comprise a unit which may be detachably connected to a host pump and heat exchanger. The unit may be removed from the system of which it is a part for upgrade and maintenance. All its components are thermally isolated from the ambient atmosphere to prevent water vapor condensation corrosion.