mmmmmmm if you have cracks in the outside panels then you have water ingress,you can check this out yourself by going in with a sharp knife or bradol in between the blinds etc from the inside,I have three windows at the front of my van and the bits between the windows where broken,(unknown till i investigated) and although they are joined top and bottom,they where broken at the joins so this must be a fault in vans as i have found this in a few now.A damp meter unless its a good one wont pick things up,Investigate before you repair as the van is now 15 years old,I have just rebuilt the front end of mine due to leaks and it was only a 1996 model.Good luck,
