[200q20v] A/C Problem(s)

[Hemberger, Chris]

It's that time of year and the A/C in my recently acquired Avant is not
functioning; ran the error codes and it appears the Low Pressure Switch is
open.  Have not yet bypassed it as a diagnostic check. Questions are:  Where
is the pressure tap to determine system pressure and is the LPS accessed
from under the hood or through the interior.  In reviewing the Bentley, the
diagram seems to indicate it is located up along the passenger-side
firewall; is this correct?  Any other suggestions for diagnosis/repair?  If
recharge is necessary - what is the general consensus?  Recharge with costly
R12 or retro-fit w/ R134a?  Any BTDTs? As always - Thanks in advance.

Chris Hemberger
91 200Q Avant