The HADES collaboration studied dielectron production in C + C , p + p , and d + p reactions, with the main goal to investigate properties of vectors mesons through their dielectron decay. Production of e+e- pairs in Ar + KCl collisions at a beam energy of 1.756 A GeV was measured recently by the collaboration and preliminary results of the experimental data analysis will be reported. Pair spectra will be compared with a prediction of a thermal model based on the Monte Carlo event generator Pluto.