It did frost up the sides and all like its supposed to do then just not cold enough.
Now that we have it all back together we pulled a vacuum and charged the unit it doesn't frost up on the sides now and we can't get it any lower than 50 degrees.
We are not familliar with the 150 here in the U.S. but it must be designed like the 55 where the cooling coils are inside the liner.
The 85 and 300 have a removable compressor/evaporator unit.
I'm not an expert but from my experiences, both instances you have described sound like a blockage in the system.
The first was a symptom of moisture in the freon, when it freezes it blocks the capillary tube and halts freon flow until it the ice melts.
The second sounds more like a solid material blocking that tube or...... a slow leak since the time you filled it.
If you removed the compressor for restoration and used the factory fittings to separate the lines, look there for a leak.
They are not trustworthy once they have been open. Eliminate them and solder the lines if necessary.
So my advice is to start over, make sure to add a new drier and test the lines to make sure there is flow, before re-charging.
http://soda-machines.com/index.php?option=com_content&task=view&id=385&Itemid=14