tapping sound from compressor after clutch& compressor replaced

[perfection777]

my ac clutch went out on my 96 ranger 2.3, picked one up at junk yard and it was sold with compressor as one, so had replaced and now comopressor is making a tapping noise. tapping like out of engine oil, but subsides after ac turned off. Also how many cans of freon should it take to charge system?

 

[killj0y]

Mine took about 2 cans from empty to full. Is the tapping the compressor clicking on and off or something else? Can you visually see it stopping and going? or anything else on it?