If compressor knocking or pounding is heard when charging with gas,
shut down at once and release some refrigerant.
When adding refrigerant use extreme care to avoid adding refrigerant
to the system too fast. Slugging and damage to the compressor could
Whenever the refrigeration system has been opened, a new
dehydrator (filter-drier) must be installed before recharging the
Two kinds of refrigerant drums are in general use. One is equipped
with a single shutoff valve and must be inverted when charging with
liquid refrigerant The other is equipped with a vapor valve and a liquid
valve, which makes it possible to charge either liquid or vapor when
the drum is upright.
Whenever available, use