A first temperature measurement of the expanded electron beam from a super-conducting magnet in the cooler of CRYRING is reported. It is based on detection of a dielectronic recombination resonance in C2+. For this measurement C3+ was stored in the ring at 3 MeV/amu energy. A fit to the resonance with free transverse and longitudinal temperatures gave 3.9 x 10(-3) eV and 4.5 x 10(-5) eV,respectively. The result is also compatible with the values of 10(-3) eV for the transverse and 6.7 x 10(-5) eV for the longitudinal component, in good agreement with expected values.