nnc0, that's exactly the reason why VNAV mode and fully managed approach is limited to the minimum OAT of -15 C at sea level. It also should be depicted on the chart till which temperature this particular approach can be flown in case of a RNAV. The reason is that the codded approach isn't ought to be modified. Unless ATC applies low temp corrections one is ought to apply it to all promulgated ALT.
Below the approved temperatures the approach will have to be flown selected with increments applied. In fact your true altitude will remain the same therefore the trajectory will be the same as well.
Cheers.
