I've never messed with the AC on a 2GNT, but I just installed AC in my GVR4 a week or so ago. If your clutch isn't engaging, it could mean one of a couple things:

1. One of your temperature or pressure switches is disconnected/faulty. I know there are TWO on the 1G DSM - 1 pressure & 1 temperature.

2. Your system has a leak and has lost refrigerant pressure. If the pressure in the system drops below some amount, the ECU will not engage the clutch to prevent compressor damage.

3. The compressor clutch itself is shot.

What to do?

1. Follow all the AC lines, looking for any kind of doo-dad with an electrical connector that screws into them. Make sure these connections are sound.

2. Was the AC blowing ice cold before it stopped working? If not, chances are you have a leak that finally got bad enough that there's no longer sufficient pressure to trip the switch, resulting in the compressor not being engaged.

3. Is the clutch itself shot? You will need to consult the factory service manual (as it's hit or miss when it comes to AC work in the Chiltons/Haynes manuals) to determine which leads carry the 12VDC to engage the magnetic clutch on the compressor. With that information, apply the voltage and listen for the click. TIP: With adequate pressure in the system and no belt on the compressor, the clutch will still engage if all is well. I confirmed my clutch worked with 225psi of Nitrogen in the lines (leak testing).

Good luck to you.