A/C Compressor Troubleshooting on an '88 5KSQ

["Christopher J. Ritchie" <cjr1@gte.net>]

Trying to determine the status of the air conditioning compressor on my
1988 5000S Quattro before I waste the $$ to recharge with R12 or convert to
134a.  I have the Bentley and am going through the troubleshooting
procedure.  Does not blow cold air when A/C switched on.  Clutch does not
seem to "click" (and compressor does not seem to engage) when A/C turned
on.  I understand that this condition is caused by either low or no
refrigerant charge, or a bad clutch or compressor.  Isn't there a way to
momentarily bridge some contacts or jumper current to the clutch in order
to determine whether the clutch is any good?  I cannot find anything in the
Bentley on this.  TIA for all suggestions.