I am trying to model a building with a direct evaporative cooler that serves multiple zones. My problem is that I am getting several hundred hours of unmet cooling loads per zone. Using hourly outputs I have calculated the effectiveness of the cooler based on supply temperature and outdoor dry and wet bulb temperatures. The effectiveness for the cooler maxes out at 51%. I ran multiple simulations, increasing the effectiveness input for the cooler from 0.1 up to 1.0. For each input the effectiveness I calculated from outputs increased until about 0.5. If I input anything higher than 0.5 it does not affect the cooler performance and the max calculated effectiveness is still only 51%.

Are there any ideas as to what is causing the evaporative cooler to lose effectiveness and not meet the loads?
Thanks for the help.

Adam Boyd