On 12 Aug 2006 23:46:46 -0700, "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?

When compressors go bad, they usually leave metal flakes at the
expansion valve filter. Black gunge suggests incompatible oil, or
inadequate flushing when changing refrigerant type.
You replaced the dryer/reservoir of course?
You filled with the recommended type and quantity of oil, I expect?
You DO have an electric clutch on the compressor drive, I suppose?
There is a cutout to the clutch for underpressure/overtemp, I expect?

Brian Whatcott Altus OK