Air con pump noise

[bigsteve1635]

Hi All

I have just brought a US speca 1996 Plymouth Grand Voyager from Germany over to the UK, but its has a strange fault with the air con compressor, when I got the van it had the electical plug to the compressor disconected the german owner was a bit vague as to why this was . Now its home, I pluged it back in and to my surpise the air con works, "yeepee" , but no there is a problem "Boo" it is as you are driving along with the air con switched on or off, every now and then the compressor makes a noise like a bad bearing but with electrical plug discounted it does not do it?????????.
I have some thoughts that maybe the fault is that there is some low voltage coming through the conector which is trying to make the clutch semi engage some how. Please help this poor soul in the UK.
PS, has anybody got a owners manual for 96 voyager