The invention relates to a tempering apparatus for tempering a sample comprising: at least one tempering block configured for receiving at least one sample, at least one tempering device arranged for tempering the tempering block, at least one temperature measurement device assigned to the tempering device, at least one control loop to which the tempering device and temperature measurement device are assigned to, at least one control device configured for control of the tempering of the tempering block, wherein the tempering apparatus comprises at least two temperature measurement devices assigned to the control loop, and that to the tempering apparatus a testing device for performing a test method is assigned to, wherein the testing device comprises a signal-connection to at least one of the at least two temperature measurement devices, such that at least one testing quantity of the tempering apparatus is detectable, which characterizes the operational status of the tempering apparatus.