just had our rear a/c unit replaced. freezing up and not cooling very well over 90 degrees. had the tech double check ducting from a/c to duct. found it wasn't done very good at factory, alot of leaks. redid the transition and tape up all the leaks. has never had that much air flow before. can feel air 1-2 feet from vent. had trouble keeping rv below 80 degrees when was in the 90's before. now a/c cycles like it should and can get down to low 70's with no problem. there seems to be a problem with the factory not knowing how to work with ducting or doesn't care.