As a distributor nozzle and thermostatic valves have low load limitations; they are poorly below these limits. If any of these devices, incorporated in packing, complete sets of equipment, there should be no low load problems. This statement assumes all other components are functioning properly. However, if the nozzle or the valve is installed in a different location, this is a potential source of malfunction, at low load. The overestimation of the component or control capacity steps incorrectly can cause problems. The excess is the most common source of these problems. Low load limit for the majority of the nozzle is about 50% of maximum capacity. For most thermostatic values, minimum load is about 30% of the maximum.
When the flow through the nozzle falls below 50%, gas and liquid refrigerant is not mixed fifty-fifty. Gas goes to the top chains, while the liquid goes into the lower. Overheating of the above ranges, is excessive, while the liquid refrigerant flooding back to compressor of the bottom circuits.
A simple way to determine the check, for higher temperatures in the pipe on top of the circuit evaporator and lower temperatures at the bottom of the tube. The solution to this problem is to replace the nozzle to the next smaller size, or to rearrange the controls to turn off one section of the evaporator to a low limit is exceeded.
When the flow through the expansion valve falls below 30%, the valve will not perform a constant parameter. He loses the ability to maintain constant overheating and starts a process called "hunting". When hunting, valve alternately overfeeds evaporator (for flooded evaporator) and then underfeeds evaporator (starving evaporator). You can define, hunting, taking of overheating readings from the temperature sensor. Readings must be taken suction line near TXV sensing bulb for a certain period of time. One reading did not give a true picture; the reading must be done over a long period of time. If overheating varies in a repeating pattern is too high, too low, hunting can be a problem. Less thermostatic expansion valve is required to solve the problem, or the refrigerant flow to the valve should be turned off when the compressor is reduced to the level of the possibilities...
Refrigeration 
