indesit ba13s fridge is not working right and freezer slighly frosting up

hi there i have a indesit ba13s and recently we have noticed that are fridge is not cooling or working at all. we recently defrosted the freezer because it had iced up. so we defrosted the appliance and left for 48hrs. now its seems the freezer is working but the fridge is not. ive test the fridge theromstat with a muitimeter and got a reading of infinty for the closed postion and zero for the open. looked up indesit website and there is no fan to assist the air flow as it natural. now we even looked for vent after searching the net that natural air flow is controlled by a vent opening up from the freezer to the fridge. which on this appliance is not apparent. also the compressor come on but only heat the coils about 30-40cm away from the compressor. please could someone advise????????