We just sold a 2 year old trailer that had the side A/C because it came with a 5000 BTU unit that could not keep it cool enough in temps above 90. The company switched to 8000 BTU units soon after we bought ours and when I contacted them about putting a larger unit in ours, they told me not to as the framing was designed around the unit and it would compromise the structure. Just before we decided to sell it, I pulled it out of the wall to see if I could find a 6000 BTU to fit hoping that may make a difference. I was not able to find any thing that would work. Mine had a vent directly above the unit and the roof was cut out so that air could get in through that vent. It does not make sense that you would have the vent, yet, the hole has not been cut out. I would call the factory customer service if I were you and ask them what the roof vent is for if no air can get in.
