Improvements to a compressor which consists in that, as soon as the measured outlet temperature (TO) reaches a certain hysteresis upper temperature limit (HMAX), the actual rotational speed of the compressor element is either lowered with a speed jump (DS) when the measured rotational speed is situated in the higher speed range close to the maximum rotational speed (SMAX), or is increased with a speed jump (DS) when the measured rotational speed is situated in the lower speed range close to the minimum rotational speed (SMIN).