Hi, cheap first thing to try is clean out the weep holes along the outside bottom of the window(s) (if one window is plugged more are likely dirty too, so do them all when you can). Use a fine gauge thin metal wire and clean the tracks of all debris etc also. Attaching a Youtube video of someone doing this as an example. The next alternative is to recaulk where the window moulding trim meets the coach wall along the top and down the sides to make sure water does not enter from that region either.