[E Rod]

You may also want to add additional Return air grills closer to the ac unit. I installed one in the center directly underneath each unit. You can feel the difference as more air is drawn into the ac. I removed one of the return grills and used a flashlight and a mirror to make sure i was making the cutout in the right place . If you cut a hole in the wrong spot, you might end up with an additional supply air to the room in which case you can cover the hole by adding another grill . I used a very small drill bit when i punch the hole through , just in case.