Yes, does it have a drier in it? If so, replace it. Sitting for four years is not good. I had to use a bolt to get the drier out. You screw the bolt into the top assembly hole. Using a prybar, lift up the bolt. The dryer pops right up. Replace your high pressure switch while the system is empty too.

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'06 X5 3.0i - bought @143,123 miles (12/26/20)