Does a TXV bulb need to be insulated if it is inside the plenum on the outlet of the evaporator?? I have a new replacement that has low cooling and the unit runs all the time. I spoke of this unit in a post earlier today but didn,t get but 1 reply...lol. If I add r22 to system or take it out my suction pressure stays at 75 pounds. Could the problem be that the bulb is not insulated, it came from the factory like that, should it be insulated?? This is a Tempstar coil.