The clutch on my a/c compressor failed and sent smoke billowing out the wheel well of my 2007 escalade esv. I ordered a new compressor (Denso 471-0316), dryer, and orifice tube. I installed the parts today and noticed that the new compressor has a plug on the back...which my old one didn't have. What is this plug for? Will the compressor work without having something plugged in here? I have an appointment to get the system recharged Monday. I hope it works!!