Is It Level?
The fridge needs to be level because the piping at the rear of the unit is at a specific angle to allow for chemical evaporation within the refrigeration process.
If the fridge is unlevelled it will affect the efficiency of the cooling process.
When the fridge is situated on the side of the van the front to back level is the most important.
If the fridge is situated at the rear of the van the side-to-side level is most important.
Time To Settle.
If the van has been moved the chemicals in the fridge would have been disturbed. If an air bubble has formed in these chemicals it will stop them from moving freely when heated.
If the fridge is left to stand for a minimum of half an hour it will allow these air bubbles to escape and the refrigeration process to proceed.
Ventilation.
The refrigeration process removes the warm air from the fridge compartment. The air needs to escape, if it doesn't then no more warmth can be removed.
Most caravans have large vents on the outside of the van these allow for free airflow around the Cooling system If these are obstructed in any way i.e. An open caravan door, it will affect the cooling.
With an awning and high temperatures in the summer, the air going into the vents can be as warm as the air coming out, also affecting the cooling of the fridge.
Still Won't Work.
If all the above factors have been addressed and it still isn't working correctly then the fridge will have to be removed and a service carried out. This should only be done by a competent person