In related question How was temperature and humidity maintained inside the Apollo mission capsules? the basic concept of conditioning Apollo mission capsules environment is described. After depressurization of the cabin though there is, obviously, no environment to condition, and during repressurization fresh oxygen needs to be supplied at high flowrate from oxygen tank at cryogenic-temperature to fill the entire cabin. What heating mechanism was applied to heat up the supply of fresh cryogenic oxygen for CM cabin repressurisation?
P.S. In original question I asked about repressurization of both CM and LM, but it seems LM stored oxygen in compressed gas form rather than cryogenic liquid or supercritical fluid, therefore I have removed LM from the question.