Schreiber Chillers 3000ACsf User Manual

Page 20

3000AC

WARNING

Overcharging a refrigeration or air conditioning system can be dangerous.

****

If a system refrigerant overcharge is sufficient to immerse the major parts of the motor and
compressor in liquid refrigerant, a situation has been created which, when followed by
unusual circumstances can lead to compressor housing seam separation or rupture.

The sequence of circumstances which can lead to compressor housing seam separation
or rupture may occur in the following manner:

(a) The system overcharge immerses the compressor motor, piston, connecting

rods, cylinder, etc., in liquid refrigerant, thereby effectively forming a hydraulic
block preventing the compressor from starting. This condition is known as
locked rotor.

(b) Electric current continues to flow through the compressor motor windings

which become, in effect, electric resistance heaters. The heat produced
begins to vaporize the excessive refrigerant liquid overcharge, causing a
rapid increase in system pressure.

during this locked rotor heating cycle(s), liquid refrigerant may be vaporized
sufficiently fast enough to raise the pressure within the system to extremes far
in excess of the housing or weld seam design limits.

(d) In some instances where the amount of refrigerant overcharge is critical in

proportion to the system internal volume, the pressure reached can cause a
compressor housing seam separation or rupture which can be hazardous.

The remedy to eliminate this exceedingly rare but potential hazard is to use correct
refrigerant charging amounts and techniques.

Tecumseh Products Company urges that all individuals responsible for training, teaching,
or advising installation mechanics and service personnel, must emphasize proper charging
techniques and strict adherence to limiting refrigerant charge amounts to those specifically
recommended by the manufacturer of the refrigeration, air conditioning, or heat pump
system.