Compressor Short Cycling

[Ivan Pillai]

Hello fellow engineers,
I've recently come across a problem with my two door Skope freezer which has a specially designed unit with a Danfoss compressor on it. I've noticed the compressor was short cycling after bringing the cabinet temperature down as far as negative 3 degrees celcius and would'nt go any futher after which i thoroughly cleaned the condensor and hence this gives the compressor ample time to cool down after being switched off. I initially suspected the start capacitor but then i have my doubts due to it working fine in the first place. What else could the cause of this be?

[martinw58]

is the system short of refrigerant

[monkey spanners]

Need to know why compressor is stopping. Does it still have power when it stops? Which would point to compressor or refrigerant problems. Or does the power cut off which would point to control issues.

[licencetochill]

Being a Scope, It will have a Carel controller, you'll have to make sure the controller is actually asking for the compressor to run, test the compressor output from the controller too prove its not faulty, or has the incorrect setpoint.
Then move onto the compressor (relay, start cap etc)

[Ivan Pillai]

Thanks friends, unit was a little over charged so i recovered the refrigerant, changed the drier, removed the old oil and fill new oil, flushed the line, vaccumed the unit and re-charged the system. It's working fine so far and cuts off at -18 degrees. Charged mostly liquid R404. controller seems to be programmed ok according to Specs.

Thanks guys!

[Brian_UK]

Thank you so much for the status update, glad to hear that the problem is resolved.