Need Help with wall mount AC outside cover

[dondrasmith]

We recently have been trying to fabricate a small gutter to help with drip from our AC, which we were able to do. In the process, we decided to take off the outside AC cover and we cleaned the old stuff from around it and checked for areas that maybe water could get in. Now we don't know what to use the seal the space between the cover and the side of the camper We have a roll of butyl tape but it is not thick enough to seal the spaces due to the curves in the aluminum siding on the camper What should we use? Has anyone ever removed the outside cover and had this same problem?