Hello, when you say the motor is working, is it the compressor at the back of the unit? The black steel ball? Is it vibrating? Hot to touch? ( be careful, it could be too hot to handle )
I don't know because it's a built-in appliance so I can't access the back of it. However the back wall seems to get colder when the motor comes on - but not enough to make the fridge cold.
Ok. Is it the back wall inside the fridge you are referring to? That gets cold but does not frost?
Oh, This is not a good sign. Definitely, it is not the thermostat because if it is the thermostat, you can not feel that the motor is running plus the fact that the inside back wall tries to cool down but not frost up is an indication that the compressor is running. If this is your case, your problem is lack of refrigerant. If the unit is lacking refrigerant, the evaporator coil would not freeze anymore but rather just cold but not freezing, just like what you are experiencing right now.
I've never heard of refrigerant - is this a substance of some sort? Is it fixable or shall I just go out and buy a replacement?
Thank you for your advice, Dr Cool.