Moisture in the system will freeze and plug the expansion valve. Extremely high discharge pressure and extremely low suction pressure indicates a clogged system.
A bad expansion valve can destroy the compressor if the valve is stuck fully open. It will flow way too much refrigerant into the evaporator. The refrigerant leaving the evaporator will still be liquid when it enters the compressor and this will blow the valves out of the compressor. It literally shatters the hardened steel valves into little pieces of shrapnel that careen around inside the aluminum compressor and absolutely destroy it. I lost one compressor that way.
Seriously forget about charging it by weight. Different receiver/dryers have different capacities and you've replaced the receiver/dryer. Get a sight glass on the discharge line between the receiver/dryer and the expansion valve and charge it until the bubbles go away. You'll ned that sight glass in the future because your system will have a slow leak and need topped off every year or so. You can't top-off by weight. I have three of these A/C systems in my garage and restored and service them all myself. Trust me on this.
'72 Jeep Wagoneer Custom, 360 V8
I love how arguements end as soon as Ristow comments. Ristow is right...again.