majonnia carbo cooler not at temp

[Waynexb]

hi everybody hoping for some help. my majonner is not achieving product tempreture of or below 2 degrees c . the product temp in is 10 degrees c and the back pressure valve is set at -2.we have always had a product temp of 4 degrees before . could there be a blockage in the carbo coolers liquid inlet. its a flooded type with a mycom 8cyl behind it.

Thanks Wayne

[RANGER1]

Try draining oil from all low points on surge drum & carbo plates ..
In some cases empty all ammonia out , then drain .
Hopefully there is drain valve on lowest points & pipework slopes towards drain valves .