Don't try to over think this.
For starters, the AC system has a high pressure cut off. It would be expected that IF the cooling fan is not running then the pressure would rise. Once above the high pressure cut off then the AC clutch is locked out to prevent damage to the compressor.
Likely the coolant boiling out is from the in-op cooling fan.
There's a fuse AND a circuit breaker protecting the fan. The fuse protects both speeds and the CB protects just the low speed. IMO if you fix the cooling fan the other problems will fix themselves.