Refrigerator revisited

Thanks all for your help, comments and suggestions in solving my 
Frigoboat refrigerator problem. But there is something odd about the 
outcome.

As advised, I bought the R12 to R134a adapter, a can of pure R134a (no 
additives) and a hose/valve asembly to hook up to the compressor 
suction-side service valve. The hose/valve assembly has a pressure gauge 
on it and a trigger-type valve actuator.

Attached adapter to service ****t. Attached hose-valve-gauge assembly to 
the adapter. Started system. Gauge showed ZERO! What? No refrigerant at 
all?

Pulled the trigger allowing gas to enter the system. Pressure quickly 
built to better than 25 psi and eva****ator started frosting. Everything 
seemed fine. Kept adding gas from time to time. Eva****ator completely 
frosted but not the exit line. Shut system down. As soon as the system 
was shut down, the pressure gauge ran up into the yellow zone, well 
above 45 psi. (Charge kit is designed for automotive air conditioners so 
don't know how significant the pressure readings are for a Danfoss 
compressor.)

Started system again. Frost very rapidly started advancing along the 
tube well past the insulated ****tion and marching toward the compressor. 
This did not happen when I first charged the system. It was now clear 
that the system had gone from apparenly no refrigerant at all to grossly 
overcharged.

I started venting refrigerant. It took a long long time before the frost 
line retreated to behind the eva****ator. The system now appears to be 
running properly but I won't know until Thursday when I again go to the 
boat. I have set the thermostat at 5 so it should cycle instead of 
running constantly..

So what happened here? The system was shut down from November to April 
and was in perfect operating condition when it was shut down. It is just 
unrealistic to believe that all the refrigerant had escaped, as 
indicated by the zero gauge reading. I suspect a clogged capillary tube. 
Rearranging the tube and banging on it did not dislodge the clog, 
wherever it was. I suspect that the system took a charge and started 
operating properly on one side of the clog. When I then shut down the 
system, all that additional refrigerant blew out the clog and caused the 
pressure to rise into the yellow zone and the frost line to advance 
rapidly toward the compressor.

Any thoughts?