I have 2 Fridgomatic 35 F (Danfoss 12 volt) constant cycling style
compressors with evaporator plates. One for my fridge and one for the
freezer. The systems are completely isolated. But, both are showing
the same brand new failure. They are running continuously and drawing
about 1/2 their usual current and periodically they stop cooling.
They have worked perfectly until now, so it may be something to do
with the change to the continental climate here in California. But,
my theory is that they are both a bit low on R-134a (their coolant of
choice) and thus not getting the boxes cool enough to ever let them
shut down and at some point tripping a thermal switch on the
compressor. Yes, no, maybe?

Since we're in a marina in CA I'd normally just call a reefer-man.
But it is Friday afternoon -- when else? So, I'm wondering how wise
it would be to see if I can find a set of gauges and add some
refrigerant. Am I likely to cause more harm than good? Are there
tricks to this that a complete novice is apt to miss? ...

-- Tom.