Norcool CU450 thermostat not working

[cyberkul]

Hi!
Got a used unit for my walk in cooler. The unit cools, but it doesn`t stop, and the temperature knob doesn`t seem to do anything. Isn`t it supposed to stop the compressor when the set temperature is reached? The defrost timer seems to be broken, but if I turn it manually the compressor stops, and the defrost light turns on. I have some used parts, and I replaced the thermostat, (the item with the purple wire..) but no change.
15621

The purple wire goes to another item with the purple wire ant two more wires at the bottom. Is this a solenoid? It is the disc shaped item in the middle of the picture. The wires doesn`t show. What is the function of this item? Can it simply be unscrewed and replaced?

15622

Thanks for any help!

[cyberkul]

It seems that the unit I replaced doesn`t have the disc shaped item. Instead it has a start capasitor. It is probably a few years newer than the unit I just installed. Both are Norcool CU-450. The reason for the replacement is a bit weak cooling capacity, and a cracked defrost "reservoir". It could be that it will help to clean the condenser, as it is probably covered with a layer of fat from cooking. I`ll try to test the therrmostats, and if necessary take the thermostat from the replaced unit.