Very often this is done with the use of a liquid temperature sensing fan speed controller. If there is no controller then you have to play fan speed controller fan speed controller and block the air flow to achieve the desired liquid pressure and temperature. Then you need to check the distributor circuits for even distribution using perhaps a surface temperature probe.
If you have uneven distribution then you can have hunting, which will worsen as the load reduces. Check to make sure that the problem is not uneven air distribution. Then you consider the evaporators rating. Xbtu/TD and you compare the ratings to the actual operating TD, return air – saturated suction. If the TD is proper then the capacity loss may be due to insufficient air flow, check how close the air-off temperature approaches saturated suction for indicators here.
If all is good, and the compressor amperage matches the charts predictions per the saturated suction and discharge conditions, then perhaps the fridge plant is undersized. What is the product? How does that systems superheated discharge temperature compare to the other good system’s SHDT? Normally, once the plant gets down past design full load and nears cut-off, if the TEV is hunting then increasing the static superheat setting by 1/4 to 1/2 turn away from the hunting point should put the hunting problem to rest.
