1. The OP is talking about aftermarket vinyl AC covers
2. Others are talking about the AC SHROUD
3. The Aftermarket is designed for storage and to keep critters/insects out of the AC system. It is not designed to be ON when traveling. There is no reason to have it on when traveling.
4. The AC Shroud MUST be installed to keep the system water tight. There are small gaps thruout the AC that if unrestricted, water is allowed to get to those areas you could have a rain leak. On some AC units the shroud MUST be installed to route the air thru the Condensor. If not installed the Compressor will overheat. Doug