You need to jump the compressor clutch with a 12v power supply. Then record what the ACTUAl low side pressure is at this time. Also, very important to make note of high side pressure as well. If the system is overcharged, theoretically, both pressures should be high. If the expansion valve is stuck, you may see a extremely low low side pressure, and a high high side pressure. Check it out some more and post the results.