Baumatic Fridge/Freezer - fridge not working?

I have a built in Baumatic Fridge/Freezer. It is located in my static caravan so I don't have the model number with me as I type. The freezer works ok but the fridge is only cool. The thermostat is in the fridge compartment, it has five settings with a sixth setting which displays a star. If you turn the themostat to the Star setting an orange light appears. Normally a fridge has a constant hum but this one although not noisy makes a sort of whooshing noise. Anyone got any suggestions please.