The portable fridge/freezer does not reach the cooling power specified. Why is this?

This could be due to various reasons:  

You have potentially placed too many and/or too warm products in the appliance. 
The lid is not closed properly or the seal is broken. 
The appliance is inadequately ventilated. There should be a minimum spacing of 100 mm from all air vents. 
The ambient temperature is too high (above 42°C). 
The temperature has been set incorrectly. 
If these measures do not eradicate the problem, then please contact Truma Service, who will be more than happy to help you.