I had the same thing with my Refrig/Freeze and the repair guy said that most times its a leak around the door seal. Take a piece of paper and put it between the door seal and where it touchs the freezer close the door see if the paper pulls out easly, if it does then you have and air leak, repeat it all the way around the door. Check the bottom side carefully. One other thing check the tempeture in the freezer it only needs to be between 0 and -5. Too cold will also cause air to be pulled through the seals.