A/C Low Pressure Switch - Where Is It?

[Lee Babcock <leebab@iesg.com>]

I have an 88 90Q, and am in the process of doing a 134a conversion.  My
compressor clutch may be shot and I want to check the low pressure
switch.  Does anyone know where it is on my car???  I did what the
Bentley said and removed the glove box and fuel injector control box, but
there didn't appear to be any switch between the blower housing and
the firewall, as promised.  Any help would be appreciated!  (Note that I'm
looking for the low pressure switch, not the low pressure inlet port on
the compressor).  Thanks!