Our's beeps is the mains voltage drops too low or the fridge door is not shut properly - sometimes it needs a good shove to stop it. As it's a new 'van I'd suggest taking it to the dealer for his comments.
Ours beeps if left open too long (intentionally) and when disconnected from the mains. If it is beeping when connected to the car and the engine is running, your car's electrics might not be wired to supply 12v to the fridge.
Ours beeps if it is switched on but there is no power from whatever it is set to use. Most noticeable when traveling and you switch to battery before you set off but the car is not yet providing power. It should be a warning that something is wrong.
We have just purchased a bailey unicorn Cordoba,, with the same annoying problem , however playing about. With the door contact a.onthe led side... pressing it in and out a few time seams to have worked...for now anyway..we have also been applying Extra hand pressure where the door locks..as to seal the magnet,s a bit more.4 Hours gone by and no bleeping as yit.