4000 relay clicking with a/c turned on

["Thomas, Nathan" <nthomas@imps0014.us.dg.com>]

Whenever I turn the a/c on in my 1985 4000S Quattro there is
an audible clicking sound every 1 - 2 seconds emitted from what
sounds like the instrument cluster.  It sounds like an electric
relay opening/closing.  When it occurs there is an ever-so-slight
loss in power to the engine- I can't even feel it by the seat of my
pants, but I can see and feel the gear shift buck a little as the 
engine lets off for a split second.  Does this sound familiar to 
anyone?  Any advice you can give on what causes this and if
there is anything I can/should do to make it go away is much
appreciated.

Nathan