Hey Gene Jim is correct, the expansion valve bulb needs to be insulated because it is operating the valve to maintain the superheat of the evaporator. Normally the TXV valve itself is not insulated, but the suction line after the valve needs to be. Some TXV valves are automatic and some are adjustable to adjust the superheat. If the valve is inside the cabinet then don't worry about it, although some are on the outside of the cabinet or A-Coil.
