Controlling metering devices

A control system for a thermal expansion valve through which refrigerant flows, the control system comprising:

• one or more heat transfer elements configured to alter a temperature of a bulb of the thermal expansion valve, wherein the bulb is configured to automatically control the thermal expansion valve, and wherein altering the temperature of the bulb alters a degree of openness of the thermal expansion valve to adjust an amount of refrigerant allowed to flow through the thermal expansion valve;
• and
• a controller coupled to one or more of the heat transfer elements, wherein the controller is configured to deliver a signal to at least one of the heat transfer elements in response to a predetermined event, and wherein the signal controls heat transfer by one or more of the heat transfer elements;
• the controller further is further configured to:
• monitor a responsiveness of the thermal expansion valve to the delivered signal;
• and
• alter the amount of refrigerant allowed to pass through the thermal expansion valve by delivering an additional signal to at least one of the one or more heat transfer elements when the responsiveness of the thermal expansion valve is outside a predetermined tolerance range.