"Akka" wrote:

We continue to have problems with our engine-driven refrigeration
system, and wondered if anybody knows what we might be doing wrong. We
keep on blowing up compressors -- either they start to leak after a
couple of months use, or they fail (i.e., no longer bring down the
low-side pressure to a vacuum). We know it's not from 'slugging' ice,
because we routinely monitor the state of the return line about 4 feet
from the compressor, and it's never frozen. When the compressors leak,
we naturally don't know it until the fridge doesn't cool anymore, when
we look at the sight glass and see it's empty. This entails running
the system for 5 minutes or more, empty, because that's how long it
takes for liquid to appear in the sight glass when the system is full.
Is that a long enough time to ruin the compressor? The last time we
opened the system up, we found some black residue blocking one of the
filters at the expansion valve. Any idea how dirt could have gotten
into the system? Maybe from a compressor going bad? How do you clean
it all out?

We have an engine driven/shore power refrigeration system that can be done either way.
The key to our particular system is not to run the engine driven refrigeration more than
45 minutes at a time. We normally do it once in the morning and once in the evening. If
you run it for more time than that, the fluids disappear to somewhere and the compressor
freezes up. We have been running ours that way since we bought the boat in 1998 (on
instructions from the PO who had the same problem as you seem to be having with blown
compressors), and have had no problems with it.

The only other thing is that we always check to see that water is coming out the exhaust
(like we do with the engine). When we run it on shore power the time isn't as critical,
but we do about the same as when we are using the engine. Otherwise it will sometimes
stop itself when it gets really cold, although it doesn't seem to hurt it when it does
that.

grandma Rosalie

S/V RosalieAnn, Leonardtown, MD
CSY 44 WO #156
http://home.mindspring.com/~gmbeasley/id1.html