I suggest you look at the BTU rating of the one you are replacing. Then, choose one with a similar rating - not less but certainly not too much higher either. To low a rating will not cool your trailer properly and too high will send a huge blast of cold air into the trailer which will cause it to cycle off, then on again as that dissipates (excessive cycling). The A/C is cooling and dehumidifying only when the compressor is operating.
- Jack