The effects of parabolic linear and step air flow maldistributions (nonuniform coil face velocities) of various magnitudes on the capacity of typical single and multi-row plate fin condensers and evaporators were considered analytically. The results indicate that for maldistributions exceeding 50% of the average coil face velocity the capacity reduction can be significant. In evaporator coils the percent loss in latent capacity is greater than the percent loss in total capacity.