AC questions/observations

I own a 1992 Ford Ranger STX with 4.0L V-6 complete with AC and it does not work. Has 189+K miles on it.

Some things I've been able to find out and/or observe

One, I thought it might be a simple electrical issue, fuse in the fuse box is fine, AC switch, part of the fan switch activates the LED indicator on the heater control panel. Also, the temp lever does not fully go to the left, cold side but I get plenty of heat when pushed all the way to the right however.

Air is not cold, fan operates just fine however in the engine compartment, the clutch does not engage, nor click so does not rotate at all. Lines out the back of the compressor do not get cold at all, rather get warm from the heat of the engine. There is no line viewer to see if any freon is flowing through or not.

I purchased this truck back in February and it was not working then. Someone said it might just be empty but even they weren't sure.

I thought the compressor would kick in no matter what the level of freon and this one does not.

So my question is, is this a mechanical, ie, compressor issue or is it something simple such as empty of coolant. Also, this system originally used R-12 coolant, will anything need to be done to convert to 134-A?

Thanks.