Same issue but how do I get the cover off the indoor unit?

do u have water draining on the outside wherever they ran the drain lines from each unit? if not , maybe they werent pitched correctly and are overflowing, those units have a tiny drain pan and must be pitched correctly on the install. Call a different contractor to check it out! And only during the summer because those units, as any AC does, remove a great deal of humidity, it isnt that humid in other seasons.