I have visited the sailing vessel Falcon, in Marina Vallarta, Mexico, and found an unusual (to me) configuration, whereby two Danfoss BD50 direct current hermetic compressors have been hooked up in parallel feeding through a water cooled condenser and a receiver to an expansion valve, holdover plate evaporator setup. To solve the obvious problem of oil misdistribution, all of the oil going to one compressor, starving the other, the unknown designer had brazed sump taps and run a 1/4" line between the two compressor sumps. According to the boat owner this system had run satisfactorily for a number of years.
However, last year, problems developed. One compressor stopped running and the other began cycling on a fault signal (the installation had no LEDs to indicate the nature of the fault. I removed the condensing unit to test on my bench. Both compressors ran independently unloaded, but when R-134a was added to where liquid began to be visible in the sight glass, with a hi side pressure of about 90 psig and a suction of about 20 psig, the individual amperage going to each compressor, climbed to about 9.4 amps and the compressors shut down on overload.
As I indicated, this configuration is new to me. The compressors are mounted side by side athwart ships, and, I surmise, when sailing healed for long periods on the same tack, all of the oil ended up in the lower compressor, starving the upper compressor, and over time both compressors experienced bearing problems leading to the overload shutdowns.
Any experience with this type of failure?