To cool heat-emitting electronic components, a compact, non-moving-parts compressor, an evaporator in juxtaposition to the electronic components and a condenser are mounted as a unit, preferably within a vacuum can. A heat exchanger is mounted external to the can but in proximity to the condenser. 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.