Air Con pressure switch

[Bill Bain <BBain@IMNET.com>]

A/C systems typically have 2 pressure switches, to prevent damage to the
compressor if the pressure is either too high or too low (don't forget
that the compressor is lubed by oil mixed in with the refrigerant).  To
check the compressor, you can often simply apply 12v to the power lead
going into the compressor and see if the clutch engages (while the
engine is running, obviously).  That will bypass the pressure switch.

Having said that, fixing A/C systems is something best left to pros.
Before I fooled with my A/C system in the Spider, I took it to an A/C
place where they diagnosed the problem as leaky compressor seals.  Since
I'm going to convert to r134a at some point, I decided not to have them
fix the seals (they have to be replaced for r134a anyway) and decided
not to fix the A/C until the whole R-124a thing shakes out..  Pay the
$20-40 and let them figure out what's wrong.   In the US, it's illegal
to vent Freon to the atmosphere, and with the price  of Freon these
days, actually converting to R134a is starting to make more economic
sense. 

Bill Bain
'83 Spider (runs much better with the O2 sensor disconnected -- why is
that?)