Door seal may need replacing or door may need adjustment , for the window wait for a good dry day ,clean all the way round the window rubber checking for cracks ,perished rubber or rot in the van body , window may need to come out for metal repair , Quick job , dry and clean the rubber inside and out , put masking tape all way round the window and reseal with a good sealant deep into the seal , allow to dry for 30-40 minutes and slowly pull away the tape , then leave over night , job done , be careful not to get any sealant in places you don't want it , its hard to clean off .