Refrigerant in the A/C system absorbs heat in the evaporator. When it does that, it changes state to vapor refrigerant, but the vapor does not change temperature. That is because the heat absorbed was consumed to cause the change of state, and the heat it absorbed is known as latent heat. When that refrigerant reaches the condenser, that latent heat is removed from the refrigerant, causing it to change state back to liquid refrigerant.

Because the liquid refrigerant absorbed heat and did not change in temperatures, when the condenser converts the vapor back to liquid, the only heat removed is that latent heat. Therefore, latent heat of condensation.

When latent heat is added or removed, the substance does not change temperature. Understand that the term latent is a Latin term meaning hidden. The heat is considered to be hidden because if you were to check both the liquid and vapor, they would be the same temperature.