Compressor Inlet Temp sensor

[rapidisimo]

On the normally closed it says "A" should be left open. Mine has a blocking nut, stud thing on it, should that be there? If I take it off air leaks completely out when I shut the engine off. With the engine running it leaks while building air, fan on but once it reaches about 90 psi it stops leaking. Is that how its supposed to be?