Originally Posted by oldskewel

90psi on high and low sides:
- the fact that it is the same on high and low means the compressor is not compressing
- the 90 psi means you probably do have liquid R-134a in there along with the R-134a gas. The gas is saturated, and from looking at the 90psi pressure, that indicates a system temperature of 82F. PDF attached here to show the pressure vs. temp relationship for a saturated vapor condition.

Attachment 78942

If you were to take the same test on a cold engine on a colder day, you'd get a lower pressure. Or on a warmed up engine, where the ambient temp in the engine bay is much higher, you'd get higher pressure readings. All completely normal and expected.

If the pressure were far below what you see on this chart, it could indicate that you do not have enough R-134a in the system to create a saturated vapor. So there would be no liquid, and only gas. Clear indication of insufficient fill. But that's not you.

On the clutch, what exactly makes you think the clutch is engaging? As is being discussed here, maybe it makes a noise, but maybe it does not fully engage. Can you see the shaft actually spinning (or not spinning)? (I don't know if that is impossible to check, but I'll ask anyway )