If your RTC module is pretty old it might be possible that it is faulty. There were a handful of boards that had a component equipped in reverse.
Not the little dot on this component. If it points inwards like in the photo it is wrong. If it points outwards like indicated by the red arrow it is correct. In case that it is wrong you can turn it yourself if you have some basic soldering skills, otherwise get in touch with the support by e-mail.
The RTC module will not store any temperature values. It only works for the time and date.