During EVA 2 of Apollo 17, Gene Cernan pointed out that having his PLSS on the "min cooling" setting was a little warm for him. That's probably because driving the lunar rover made his metabolic rate ~10% higher than Jack Schmitt's. Cernan even asked mission control if his cooling was working fine.
Why didn't he simply increase the cooling setting of his PLSS while driving? If the astronauts had to follow a strict cooling water rationing protocol (e.g. only use the "min cooling" setting while riding the LRV), where can I read more about it?
I understand that the astronauts had to ration cooling water (and other resources), but was there a protocol in place forcing them to use the "min cooling" setting on the while riding the LRV? (This particular EVA was the longest of all Apollo missions).