This paper compares two alternative models for investigating temperature and moisture distributions in air–air enthalpy exchangers. The first model is based on a 2D parallel-plate counterflow approach while the second one includes both counterflow and crossflow regions by accounting for the 3D geometry of the exchanger. In both models, the temperature and moisture fields in the exhaust and supply air are determined by coupling the governing heat and moisture transfer equations with velocity and pressure distributions obtained by computational fluid dynamics. Moisture transfer through the semi-permeable membrane is modeled by applying a moisture-dependent resistance to vapor diffusion. Numerical simulations are performed using COMSOL Multiphysics. The models are validated against experimental data found in the literature. While the 2D model shows significant deviations, the 3D model demonstrates a better agreement with the measured data.