This was to replace a Dometic Brisk Air II, which worked just long enough for the warranty to expire. It is plug and play. No need to switch out the thermostat or relay box. Remember that the relay box is not part of ac—leave it dangling until you hook the new ac into it—it is part of the thermostat system. This worked with my vented system just fine, but would also work with ventless. The switch-out/install was easy. The tough part is getting it onto the roof. It is much quieter than the Dometic and cools better—much better. The bg unknown is how long it will last. I will certainly revise my review if it does not significantly outlast he Dometic piece of junk. My Dometic fridge was an equal piece of worthlessness—replaced with residential unit.
