I can hear a similar noise from the rear a/c of my '97 T&C. Right when I turn it on for a few seconds. It's always done it and worked fine, I figured it was just the expansion valve opening up or something. 12 years on the original a/c and still ice cold, thats what I'm talking about.
2001 Infiniti i30 3.0 DOHC V6: VQ30DE 177,000 miles; 1999 Nissan Altima GLE KA24 168,000 Miles
1997 Dodge Ram 1500 SLT Laramie 5.9 46RE, 182,000 Miles
Prev. 97 T&C LXi 184k 3.8, 94 T&C 3.8 156k Miles, 93 GV LE 3.3 123k