Sounds like condensation. You either to completely isolate the two enviroments, or let them equalize. It sounds like air in one condition is getting trapped in the cluster, and is not able to get out. If you vent it, then you will need to worry about moisture getting in when you dont want it to... if you perfectly seal it then you need to perfectly seal it, so-so isnt going to cut it.
That works whether with pretty much any situation dealing with condensation.