There is no hydraulic fluid in the transmission. However, there is hydraulic fluid in the clutch system. If the clutch fluid reservoir is empty it would cause clutch not to operate.
yes hydraulic could cause this also the clutch pressure plate could be collapsed
bad clutch cable, or not enough oil on the clutch plates.
BAD clutch slave cylinder, wore out clutch and pressure plate.
if its hydraulic there could be air in your line. bleed your clutch and refill.
Check the fluid level first, but beyond that, any internal wear which allows hydraulic pressure leaks would cause the problem you describe. It could be a clutch pack, valve body, hydraulic pump or even a partially plugged filter.
Bad hydraulic cylinders.
First, the clutch won't engage if the refrigerant level is low. Start there. Next, check the sensor at the receiver/dryer.
cause your stupid
Bad or worn friction disc, faulty clutch fork, faulty throwout bearing, clutch out of adjustment... pick your poison.
What specific kind of vehicle do you have? It does sound like the clutch may be bad, but we also need to know what you are working on. You need to run power straight from the battery to the compressor. If is still does not engage then you need to replace the compressor and clutch, they are dead. If they do engage, then you have a wiring or computer issue.
It is a hydraulic clutch. An excess of fluid in the system will cause it to be hard to pull back. Either that, or you need to lift some weights so that you won't notice.
It would be bypassed by the mode door in the ducting under the dash. You may have have a problem with your mode door if your compressor is turning on when you select A/C. If the compressor clutch does not engage it is likely that there is an insufficient charge in the system, and you may have a leak.