Waeco RPD 215L Fridge

i have a new caravan with a Waeco RPD 215L 12volt fridge, has anyone had trouble with these fridges? I have had 3 previous 12v 190L Waeco and no problems at all, but this new model seems to ice up on the cooling panel all the time, and cycles on and off for about 45 minutes at a time, hence the fridge is not staying very cold.

Kerri, QLD