Hi,

  My Mom's 94 Chev Lumina (V6  3.1 liter) A/C stopped working. In a process
of elimination (see "Test Results" below),  I have eliminated  some things
already.  Note: The A/C compressor clutch doesn't engage when A/C is turned
on.   According to Haynes service manual, this car (3.1 liter engine) doesn't
have pressure switches (I couldn't find any).

  I removed the connector (3 wires) from the A/C pressure sensor.
This sensor symbol in a Haynes service manual looks like a potentiometer
with ground on one end, +5V on the other and a wiper arm (pressure).
The wires run to the ECM.   It is extremely difficult to measure the sensor
resistance so I can use a regular "pot" of the same resistance to simulate
the pressure sensor.  

  A Google search did not reveal the information I need.

  Do you know any tricks to eliminate the pressure sensor?

               Thanks in advance,   Brad

  TESTS RESULTS:

  My cousin brought his A/C pressure gauge and said the pressure was normal
(checked on low side) with engine running A/C on "MAX".

  I checked the A/C relay in my service shop and checked the "HVAC" fuse
(only fuse for AC).  I disconnected the connector from the compressor clutch
and checked for voltage with engine running and A/C on "MAX".  No voltage.