How Tall?

What are the ambient temps in the room that you are drawing air from?
Take you thermometer or hygrometer whatever you use and measure the temps outside the "room".
You can only get your temperatures down to the temp of the air you are pulling in.
Hence, if it is 80F outside the room you won't get your room below 80F ever...(without an airconditioner)

thnx blink,

my temps in the room the cab is in are around 76-79 during the hottest part of the day and at night it gets down around 66-68. I do have a lil swamp cooler i can put on the floor beside the intake. do you think that would help?