First post here, so a little background on me. I am 29 years old and have been in the hvac-r industry since I was 15(summers). I have always been more on the refrigeration side than the hvac side, but do both. I have searched for answers to my problem, but nothing pops out at me. I have a 2 year old walk-in freezer that the box was put up by a restaurant equipment installer, and we installed the refrigeration. It has recently come to my attention that the door absolutely will not open for at least a minute after it is closed. This caused major panic in one of the workers as she felt trapped. The detective work I did makes me believe this has been going on since day 1. So, I found the heated vent to be working properly and free of ice. When you close the door, the air just screams through the vent. I tried shutting down the refrigeration system and the same problem occured. I tried opening an outside door to relieve building pressure, same problem. Could it be the heated vent is just too small? The box is a Master-Bilt approx 12x8 with 9' ceiling and only has a 2'' vent. Any ideas?