On Astraea our Fridge uses two different ways to make the icebox cold. We have two refrigeration compressors, one run off 115VAC shore power (or our Honda 2000 generator when we’re away from the dock), the other loop runs off the engine. The two compressors pressurize refrigerant to make holding plates in our icebox cold. Each compressor’s loop is separate so that if one side breaks or leaks we can use the other to keep our food cold.
After fixing broken refrigeration lines and sealing leaks I didn’t properly secure the holding plates in the refrigeration box. Some refrigerant leaked out of both loops and decreased the efficiency of our fridge. Natalie helped me secure the cold plates with wooden blocks and I tightened all the connections.
I was out of refrigerant and ended up taking an afternoon to find more in La Paz where we’re anchored. It took trips to a half dozen different hardware and auto parts stores before I found what I needed. The threads on a giant bottle of refrigerant at El Arco (a hardware store) were smaller than the standard American style refrigerant bottle I was used to and there was no adapter, so be careful if you end up looking for refrigerant in Mexico because that bottle did not fit the gage set.
Our thermometer in the ice box used to read the air temperature of the box, but that made it difficult when charging to know when the cold plates were getting cold quickly and the refrigerant charge was correct. I relocated thermostat thermometer behind our smaller cold plate and held in place with foam to read the temperature directly off the cold plate.
Then I recharged the engine driven loop using our refrigerant gage set using notes from our boat’s manuals.
Normal pressure for suction is 15 psig at start (warm box); -5 to -10 at end of cycle (cold box)
Normal pressure for discharge is 135 to 140 psig. Higher at beginning of cycle than at end of cycle (cold box). Higher pressure is probably normal but ok to 150 psig. High pressure is caused by lack of water flow through condenser or air in the system. End of cycle (cold box) pressure should be 100 to 120 psig.
When plate is coldest (8 degrees F on thermostat) pressure is 3 on low side, 96 high side with moderate stream of bubbles in sight glass.