Sounds like you don't have enough R-12 in the system if you can still see
bubbles in the sight glass. A full system normally gives no indication of
bubbles, thus you can't see anything moving in the sight glass. However, 38
psi on low side should certainly be enough to at least operate the system. I
like to hold the can while viewing the sight glass and stop adding coolant
when the bubbles stop. This may well get you more than 38 psi on the low
side but that's usually okay anyway.

You said you hot wire jumped the pressure switch. Is this actually what you
did rather than put a jumper between the two connections on the pressure
switch plug? This is a two-prong switch connector which you should hot-wire
first rather than the compressor anyway. Hot wiring the pressure switch
itself does nothing.

I'm guessing the problem is the pressure switch if the compressor runs when
you jumper the switch plug. Problem is you normally have to take the switch
out to check or replace it. There is a way to check the circuit if you have
another switch laying around and an air compressor. Take the uninstalled
switch, plug the connector onto the two terminals, start your car and turn
the AC unit on. Take an air nozzle with a rubber tip and press it tightly
against the air orifice on the bottom of the switch where it screws into the
drier. If the compressor comes on when you apply air pressure your existing
switch is bad. If it doesn't, and you are sure you're getting pressure to
the switch, then the problem is somewhere else in the system.

If that is the case your dash control may well be the source although you
say the fan works properly.

How much R-12 did you say you had? Changing the pressure switch means
draining the entire system and starting over.

To all you environmentalist kooks, please don't tire me with those claims
about that alleged hole in the ozone caused by cfc, etc. That's a proven
cyclic event that takes place every 50 years or so.

Good luck Gary.